feat(library): icon-based row-action buttons on Instantiated tab (#830)

## Summary

Replaces the text-labeled Select / Teleport / Remove buttons on each row
of the Library's Instantiated tab with icon-only colored beveled squares
(80×80). The three buttons preserve their previous semantic hierarchy
via the existing `AcceptButton` (green) / `StandardButton` (blue) /
`CancelButton` (red) prefab styles.

### User-affecting changes

- **Buttons are icon-only.** The existing localization keys
(`library.select`, `library.deselect`, `library.teleportTo`,
`library.remove`) remain in the locale files for future tooltip / a11y
use, so no translations are lost.
- **Buttons are hidden (not just disabled) for scene-mode and embedded
instances.** Previously these rendered as disabled buttons that still
occupied row width and added visual noise. The underlying scene-unload
code paths in the OnClicked handlers are intentionally left in place so
the functionality can be exposed via a different UI surface later — only
the library-window entry point goes away.

### Sprite additions (`com.basis.sdk`)

| Sprite | Source | Status |
|---|---|---|
| `scan-outline.png` | Ionicons | new |
| `link-outline.png` | Ionicons | new, consumed by follow-up
trackerobjects integration PR |
| `unlink-outline.png` | Ionicons | new, consumed by follow-up
trackerobjects integration PR |
| `trash-bin-outline.png` | already on disk | newly registered as
addressable in the Basis UI Assets group |

All sprites match the existing project icon convention: white-stroke
RGBA at 512×512 on transparent background. Source:
https://github.com/ionic-team/ionicons (MIT). PNGs rendered from the
upstream SVGs.

### API additions

Five new entries on `AddressableAssets.Sprites`: `Select`, `TeleportTo`,
`Trash`, `Link`, `Unlink`. `TeleportTo` aliases the existing
`Teleport.png` (was only exposed via `Respawn` before). `Link` and
`Unlink` ship here for the follow-up trackerobjects integration package
PR to consume.

## Required checks
All boxes below must be ticked before this PR can merge. If a check is
genuinely N/A, tick it anyway and explain under **Notes**.

<!-- required-checks-start -->
<!-- Tick the boxes in place — do not edit the line text. The
pr-checklist workflow parses this block; per-PR context goes under
Notes. -->
- [x] **Tested** — I built and ran this locally. The change works in the
editor and (where relevant) in a built player.
- [x] **Transform access is combined and limited** — In hot paths,
transform reads/writes go through `TransformAccessArray` or are
otherwise batched. I have not added per-frame `transform.position` /
`transform.rotation` / `transform.localPosition` calls inside loops.
Whenever I need both position and rotation, I use the combined APIs —
`SetPositionAndRotation` / `SetLocalPositionAndRotation` for writes,
`GetPositionAndRotation` / `GetLocalPositionAndRotation` for reads —
instead of two separate property accesses; the combined call does one
local-to-world matrix traversal instead of two.
- [x] **Addressables used for asset/memory loading** — Any new asset
loads go through Addressables. No new `Resources.Load`, no direct asset
references that pull large content into memory on scene load.
- [x] **No new `GetComponent` / `AddComponent` where avoidable** — Where
unavoidable, the result is cached on a field, and any `GetComponent<T>`
is replaced with `TryGetComponent<T>(out var x)` — bare `GetComponent`
will be denied. `TryGetComponent` is the modern API (Unity 2019.2+) and
skips the Editor-only GC allocation `GetComponent` causes when a
component is missing: Unity wraps the `null` return in a managed "fake
null" object so its overloaded `==` operator can still detect destroyed
C++ objects, and constructing that wrapper allocates; `TryGetComponent`
returns a `bool` plus `out` parameter and never builds the wrapper. None
of these calls run inside `Update`, `LateUpdate`, `FixedUpdate`, jobs,
or other per-frame code paths.
- [x] **Per-frame work is scheduled through `BasisEventDriver`** — Any
new per-frame work hooks into `BasisEventDriver` rather than adding
standalone `Update` / `LateUpdate` / `FixedUpdate` callbacks on a
MonoBehaviour.
- [x] **Considered jobification** — I asked whether this work can be
moved to a Unity Job (Burst-compiled where possible). If it can, it is.
If it cannot, the reason is in **Notes**.
- [x] **No needless `{ get; set; }` properties or access lockdowns** —
Public fields are fine; Basis is meant to be read and modified freely,
so don't wall things off `private`/`internal` without a real reason.
Don't wrap a field in `{ get; set; }` when the accessors do nothing —
property accessors have a real performance cost vs direct field access,
and the lead maintainer prefers plain fields (or a method / setter-only
property when only the setter needs logic) over a noop-getter pair. For
`.Instance` singletons, callers reassigning `Type.Instance` is allowed;
if that would break your code, log a warning or throw — don't block the
assignment. Locking down access is not your call.
- [x] **Camera access goes through `BasisLocalCameraDriver`** — Code
that needs the local camera (transform, projection, rig data, etc.)
pulls it from `BasisLocalCameraDriver` rather than looking one up
itself. Don't roll a separate camera discovery path.
- [x] **Logging uses `BasisDebug`** — All new logging calls go through
`BasisDebug.Log` / `BasisDebug.LogWarning` / `BasisDebug.LogError` (with
an appropriate `LogTag`) instead of `UnityEngine.Debug.Log` /
`Debug.LogWarning` / `Debug.LogError`. `BasisDebug` routes through
Basis's tagged, color-coded logger and respects the project-wide
`LoggingDisabled` toggle so logging can be killed at runtime; bare
`Debug.Log` calls bypass that and will be denied.
- [x] **No scene-wide discovery for dependencies** — New code is
architected so it does not need `FindObjectOfType` / `FindObjectsOfType`
/ `GameObject.Find` / `FindGameObjectsWithTag` to locate what it depends
on. References are wired in — registered through an existing
manager/driver, injected at init, or passed in by the caller — rather
than discovered by scanning the scene at runtime. If a scene scan is
genuinely unavoidable, justify it under **Notes**.
- [x] **No allocations in hot paths** — Per-frame code (Update /
LateUpdate / FixedUpdate, simulation loops, jobs, anything called once
per frame or more) does not allocate. No `new` on reference types, no
LINQ, no `string` concatenation/interpolation, no boxing, no `foreach`
over interface-typed collections. Allocate once at init and reuse the
buffer.
- [x] **No debugging in hot paths** — No log calls of any kind on
per-frame paths, including `BasisDebug`. Hot-path logging floods the
console and incurs cost on every frame regardless of whether the message
is filtered out downstream. If a hot-path log is needed while iterating,
gate it behind `#if UNITY_EDITOR` and remove (or leave gated) before
merge.
- [x] **Hot-path collection access is optimized** — Cache `.Count`
(lists) / `.Length` (arrays) into a local `int` before the loop instead
of re-reading the property each iteration. Prefer `T[]` (with a separate
length int when the array is over-sized) over `List<T>` where the data
is hot — Unity's mono BCL doesn't expose
`CollectionsMarshal.AsSpan(List<T>)`, so a list can't be fed into
`Span<T>` / unsafe paths cleanly. Where the perf justifies it, drop into
`Span<T>` / `ref` locals / `Unsafe.As` / `unsafe` pointer code to skip
bounds checks and copies, and call out the invariants you're relying on
under **Notes** so reviewers can sanity-check them.
<!-- required-checks-end -->

## Testing details
Tick the platforms you actually tested on. Leave the rest unticked —
these are informational and do not block merge.

- [x] Windows
- [ ] Linux
- [ ] Android
- [ ] iOS
- [ ] macOS

Input / control mode coverage:

- [ ] Tested in VR (note headset under **Notes**)
- [x] Tested in desktop / non-VR mode
- [ ] Tested with phone controls (mobile touch input)
- [ ] N/A — change does not touch player/XR/input code

Where applicable, confirm these flows still work after your changes:

- [ ] Hot-switching (desktop ↔ VR mode swap at runtime)
- [ ] Avatar swapping
- [ ] Server swapping (joining / leaving / changing servers)
- [x] N/A — change does not touch any of the above

## Notes

- **Required-check N/A justifications.** This is a UI-only change:
row-button restyling plus a few new addressable sprite entries. No
transform access, no per-frame work, no jobification candidates, no
camera access, no new logging, no scene-wide discovery, no hot-path
code, no `GetComponent`/`AddComponent` additions, no `{ get; set; }`
lockdowns. Existing `TryGetComponent<Button>` calls in
`LibraryProvider.CreateListEntry` are retained unchanged. The
required-checks boxes are ticked because the project's checklist rule is
to tick + explain N/A items here; they aren't claims that the diff
exercised those code paths.
- **Verified live in the editor.** Buttons were iterated visually across
multiple in-game reviews — caption crowding, icon stroke colour (white
to match the existing Ionicon set), and the colored-bevel vs Hotbar
layout were all tightened based on what rendered correctly on a real
avatar + prop spawn.
- **Scene/embedded unload code paths intact.** The `OnClicked` handlers
for Teleport and Remove still contain their original `case
SpawnMode.Scene` branches and the `case SpawnMethod.Embedded`
fall-through label — the early return at the top of `CreateListEntry`
simply prevents this UI surface from ever reaching them. Those code
paths predate this PR and may want to be surfaced via a different UI (a
moderator panel, perhaps) in a follow-up; deliberately not removed here.
- **Follow-up trackerobjects PR** depends on this one merging first so
that `AddressableAssets.Sprites.Link` / `.Unlink` resolve at compile
time. Its branch is `feat/trackerobjects` on this fork; the icon-swap
commit on that branch is held back until this lands.

Author: dooly123

Basis/Assets/AddressableAssetsData/AssetGroups/Basis UI Assets.asset

@@ -116,6 +116,11 @@ MonoBehaviour:
     m_ReadOnly: 0
     m_SerializedLabels: []
     FlaggedDuringContentUpdateRestriction: 0
+  - m_GUID: 2b9d4f1a7e8c3b6d5a2f9e1c4b7a8d3f
+    m_Address: Packages/com.basis.sdk/Textures/Runtime/unlink-outline.png
+    m_ReadOnly: 0
+    m_SerializedLabels: []
+    FlaggedDuringContentUpdateRestriction: 0
   - m_GUID: 2f02813bc29de864cb7a5a27364ee32a
     m_Address: Packages/com.basis.sdk/Prefabs/Panel Elements/PE Image Simple Square.prefab
     m_ReadOnly: 0
@@ -179,6 +184,11 @@ MonoBehaviour:
     m_ReadOnly: 0
     m_SerializedLabels: []
     FlaggedDuringContentUpdateRestriction: 0
+  - m_GUID: 4e8a2c9b1d3f6e7a8b9c0d1e2f3a4b5c
+    m_Address: Packages/com.basis.sdk/Textures/Runtime/scan-outline.png
+    m_ReadOnly: 0
+    m_SerializedLabels: []
+    FlaggedDuringContentUpdateRestriction: 0
   - m_GUID: 50f97b6b5d2b5cd4993f1fd38883bde8
     m_Address: Packages/com.basis.sdk/Sprites/Icons/Exit.png
     m_ReadOnly: 0
@@ -248,6 +258,11 @@ MonoBehaviour:
     m_ReadOnly: 0
     m_SerializedLabels: []
     FlaggedDuringContentUpdateRestriction: 0
+  - m_GUID: 75dcae065f0db18479883c0f554885bf
+    m_Address: Packages/com.basis.sdk/Textures/Runtime/trash-bin-outline.png
+    m_ReadOnly: 0
+    m_SerializedLabels: []
+    FlaggedDuringContentUpdateRestriction: 0
   - m_GUID: 7789be676b03fdd4f8d2e4b183e25858
     m_Address: Packages/com.basis.sdk/Textures/Runtime/clock.png
     m_ReadOnly: 0
@@ -263,6 +278,11 @@ MonoBehaviour:
     m_ReadOnly: 0
     m_SerializedLabels: []
     FlaggedDuringContentUpdateRestriction: 0
+  - m_GUID: 7f3a1d8b4c6e9f2a5b8c3d1e6f4a9b2c
+    m_Address: Packages/com.basis.sdk/Textures/Runtime/link-outline.png
+    m_ReadOnly: 0
+    m_SerializedLabels: []
+    FlaggedDuringContentUpdateRestriction: 0
   - m_GUID: 7f82d6af13c883d4b885adbeab63a58d
     m_Address: Packages/com.basis.sdk/Textures/Runtime/exit-outline.png
     m_ReadOnly: 0

Basis/Packages/com.basis.framework/BasisUI/Addressables/AddressableAsset.cs

@@ -40,6 +40,13 @@ public static class Sprites
             public static string MicrophoneMute = "Packages/com.basis.sdk/Textures/Runtime/microphone-mute-solid.png";
             public static string People = "Packages/com.basis.sdk/Textures/Runtime/people-outline.png";
 
+            // row-action icons (Library Instantiated tab)
+            public static string Select = "Packages/com.basis.sdk/Textures/Runtime/scan-outline.png";
+            public static string TeleportTo = "Packages/com.basis.sdk/Textures/Runtime/Teleport.png";
+            public static string Trash = "Packages/com.basis.sdk/Textures/Runtime/trash-bin-outline.png";
+            public static string Link = "Packages/com.basis.sdk/Textures/Runtime/link-outline.png";
+            public static string Unlink = "Packages/com.basis.sdk/Textures/Runtime/unlink-outline.png";
+
             // embedded items
             public static string Embedded = "Packages/com.basis.sdk/Textures/Runtime/embedded.png";
 

Basis/Packages/com.basis.framework/BasisUI/Menus/Library/LibraryProvider.cs

@@ -1944,17 +1944,18 @@ private static void CreateListEntry(BasisRuntimeSpawnRegistry.SpawnInstance item
             itemTextInfo.Descriptor.SetHeight(50);
             itemTextInfo.Descriptor.SetWidth(400);
 
-            PanelButton selectItem = PanelButton.CreateNew(ButtonStyles.AcceptButton, itemListPanel.TabButtonParent);
-            selectItem.Descriptor.SetTitle(hasSelected ? BasisLocalization.Get("library.deselect") : BasisLocalization.Get("library.select"));
-            selectItem.SetSize(new Vector2(200, 60));
-
-            // determine if we can select this item
-            if (selectItem.Descriptor.gameObject.TryGetComponent<Button>(out Button selectButtonComponent))
+            // Skip the row-action buttons for scene-mode and embedded rows — not user-owned spawns.
+            if (itemKey.SpawnMode == BasisRuntimeSpawnRegistry.SpawnMode.Scene
+                || itemKey.SpawnMethod == BasisRuntimeSpawnRegistry.SpawnMethod.Embedded)
             {
-                // for the moment disable selecting embedded items
-                selectButtonComponent.interactable = (itemKey.SpawnMode != BasisRuntimeSpawnRegistry.SpawnMode.Scene) && !(itemKey.SpawnMethod == BasisRuntimeSpawnRegistry.SpawnMethod.Embedded);
+                return;
             }
 
+            PanelButton selectItem = PanelButton.CreateNew(ButtonStyles.AcceptButton, itemListPanel.TabButtonParent);
+            selectItem.Descriptor.SetTitle(string.Empty);
+            selectItem.SetIcon(AddressableAssets.Sprites.Select);
+            selectItem.SetSize(new Vector2(80, 80));
+
             selectItem.OnClicked += async () =>
             {
                 if(hasSelected)
@@ -1975,14 +1976,9 @@ private static void CreateListEntry(BasisRuntimeSpawnRegistry.SpawnInstance item
             };
 
             PanelButton TeleportToItem = PanelButton.CreateNew(ButtonStyles.StandardButton, itemListPanel.TabButtonParent);
-            TeleportToItem.Descriptor.SetTitle(BasisLocalization.Get("library.teleportTo"));
-            TeleportToItem.SetSize(new Vector2(200, 60));
-            // dont let the teleport button work for scenes yet
-            if (TeleportToItem.Descriptor.gameObject.TryGetComponent<Button>(out Button teleportButtonComponent))
-            {
-                // if the item is embedded only allow an admin to interact
-                teleportButtonComponent.interactable = !(itemKey.SpawnMode == BasisRuntimeSpawnRegistry.SpawnMode.Scene);
-            }
+            TeleportToItem.Descriptor.SetTitle(string.Empty);
+            TeleportToItem.SetIcon(AddressableAssets.Sprites.TeleportTo);
+            TeleportToItem.SetSize(new Vector2(80, 80));
 
             TeleportToItem.OnClicked += () =>
             {
@@ -2013,8 +2009,9 @@ private static void CreateListEntry(BasisRuntimeSpawnRegistry.SpawnInstance item
             };
 
             PanelButton removeItem = PanelButton.CreateNew(ButtonStyles.CancelButton, itemListPanel.TabButtonParent);
-            removeItem.Descriptor.SetTitle(BasisLocalization.Get("library.remove"));
-            removeItem.SetSize(new Vector2(200, 60));
+            removeItem.Descriptor.SetTitle(string.Empty);
+            removeItem.SetIcon(AddressableAssets.Sprites.Trash);
+            removeItem.SetSize(new Vector2(80, 80));
 
             // only apply this to items that are spawned on the network
             if(itemKey.SpawnMethod == BasisRuntimeSpawnRegistry.SpawnMethod.Network)