chore(app-shell): remove legacy monolith detail renderer + renderViaSchema kill-switch (ADR-0085 PR4)

RecordDetailView now always renders through the SchemaRenderer Page
pipeline: an authored PageSchema(pageType='record') when assigned, else
the buildDefaultPageSchema synthesis. The non-schema-driven monolithic
DetailView branch and both entry points are removed:

- objectDef.detail?.renderViaSchema === false (the last surviving
  detail.* key — ADR-0085 removed the block from the spec, keeping this
  key only as the kill-switch) is no longer read;
- the ?renderViaSchema=0 debug URL param is no longer honored.

Also drops the legacy-only plumbing this branch required: the eager
per-record related-lists fan-out (the schema path's record:related_list
self-fetches lazily per tab) and the intermediate DetailViewSchema
translation layer, now replaced by a synthParts memo that feeds
buildDefaultPageSchema directly. The DetailView component itself stays
in @object-ui/plugin-detail (still used by the record:details renderer).

Removes the now-dead `DetailView`/`RecordChatterPanel` import in
ObjectView and updates the slotted-pages guide.

Closes #2181

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01VRBZFKwqib3pjPUua3LjCP

Author: claude

.changeset/adr-0085-pr4-remove-legacy-detail-renderer.md

@@ -0,0 +1,21 @@
+---
+"@object-ui/app-shell": patch
+---
+
+chore(app-shell): remove the legacy monolith detail renderer + the `renderViaSchema` kill-switch (ADR-0085 PR4, #2181)
+
+`RecordDetailView` now always renders through the SchemaRenderer Page
+pipeline (an authored `PageSchema(pageType='record')` when assigned, else
+the `buildDefaultPageSchema` synthesis). The non-schema-driven monolithic
+`DetailView` branch and both of its entry points are gone:
+
+- `objectDef.detail?.renderViaSchema === false` is no longer read (it was
+  the last surviving `detail.*` key — ADR-0085 removed the block from the
+  spec, and the key had been kept only as this path's kill-switch);
+- the `?renderViaSchema=0` debug URL param is no longer honored.
+
+Also drops the legacy-only plumbing: the eager per-record related-lists
+fan-out (`record:related_list` self-fetches lazily on the schema path)
+and the intermediate `DetailViewSchema` translation layer. The
+`DetailView` component itself remains in `@object-ui/plugin-detail`
+(still used internally by the `record:details` renderer).

content/docs/guide/slotted-pages.md

@@ -110,9 +110,7 @@ The two modes are mutually exclusive: a page either has `kind: "full"`
 (default) and uses `regions[]`, or `kind: "slotted"` and uses
 `slots`.
 
-## Disabling the synthesizer entirely
-
-The default-page synthesizer is on by default. To fall back to the
-legacy DetailView monolith for an object (typically for debugging a
-regression), set `objectDef.detail.renderViaSchema = false`, or pass
-`?renderViaSchema=0` in the URL.
+> **Note:** the default-page synthesizer is the only render path for
+> record detail pages. The legacy monolithic DetailView fallback and its
+> `renderViaSchema` kill-switch (`objectDef.detail.renderViaSchema`,
+> `?renderViaSchema=0`) were removed by ADR-0085 PR4.

packages/app-shell/src/views/ObjectView.tsx

@@ -20,7 +20,6 @@ const ImportWizard = lazy(() =>
   import('@object-ui/plugin-grid').then((m) => ({ default: m.ImportWizard })),
 );
 import { ListView } from '@object-ui/plugin-list';
-import { DetailView, RecordChatterPanel } from '@object-ui/plugin-detail';
 import { ObjectView as PluginObjectView, ViewTabBar, ManageViewsDialog, deriveRecordSurface, overlayWidthFor } from '@object-ui/plugin-view';
 import type { ViewTabItem } from '@object-ui/plugin-view';
 import { RECORD_DRAWER_PARAM } from '../urlParams';