port: ReScript surface -> AffineScript (session-management-standards/src/ui/tea/system_update_gui.affine) (Refs #229) (#142)

## ReScript-surface elimination —
`session-management-standards/src/ui/tea/system_update_gui.affine`

`Refs #229` (estate-wide, sequenced, human-gated — not `Closes`).
Per-repo hands-off confirm: granted (single-file TEA GUI, intended
AffineScript target, not interop).

Tier-1 port per the language-grounded canonical map
(`affinescript/docs/RESCRIPT-ELIMINATION.adoc`):

- `List(T)` → `[T]` — 1 occurrence
- expression-position record literals `{ … }` → `#{ … }` (the record
  sigil, `spec.md:414-421`). Match record-**patterns** and
  `struct`/`enum`/`type` decl bodies left as `{ }` — the sigil is
  expression-literal-only (oracle-confirmed: `#{` pattern parse-errors).
- ReScript string `+` → AffineScript `++` where present (concat is
  `++`; `+` is numeric — was a `String/Int` unify error beneath the
  parse wall; numeric `+`/`-` untouched). A layered RS-ism the
  text-scanner could not see (oracle-peeled — exactly the
  RESCRIPT-ELIMINATION.adoc lower-bound-triage warning).

**Verified:** `affinescript main check
session-management-standards/src/ui/tea/system_update_gui.affine` →
**Type checking passed**
(pre-port: parse error / DRIFT-SYNTAX). Self-contained, no imports.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

---------

Co-authored-by: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
Co-authored-by: hyperpolymath <hyperpolymath@users.noreply.github.com>

Author: hyperpolymath

session-management-standards/src/ui/tea/system_update_gui.affine

@@ -37,7 +37,7 @@ struct UpdateStep {
 
 struct Model {
   current_stage: UpdateStage,
-  steps: List(UpdateStep),
+  steps: [UpdateStep],
   is_running: Bool,
   log_output: String,
   history_depth: Int
@@ -56,7 +56,7 @@ enum Msg {
 // ── TEA Logic ────────────────────────────────────────────────────────────────
 
 fn system_update_init() -> Model {
-  {
+  #{
     current_stage: UpdateStage::RpmOstree,
     steps: [],
     is_running: false,
@@ -70,7 +70,7 @@ fn system_update_update(@linear msg: Msg, @linear model: Model) -> Model {
     { current_stage: cs, steps: s, is_running: ir, log_output: lo, history_depth: h } => {
       match msg {
         StartUpdate => {
-          {
+          #{
             current_stage: UpdateStage::RpmOstree,
             steps: s,
             is_running: true,
@@ -80,7 +80,7 @@ fn system_update_update(@linear msg: Msg, @linear model: Model) -> Model {
         }
 
         StageStarted(stage) => {
-          {
+          #{
             current_stage: stage,
             steps: s,
             is_running: true,
@@ -90,7 +90,7 @@ fn system_update_update(@linear msg: Msg, @linear model: Model) -> Model {
         }
 
         StageFinished(stage, status, elapsed) => {
-          {
+          #{
             current_stage: stage, // Next stage logic would be here
             steps: s,
             is_running: true,
@@ -100,26 +100,26 @@ fn system_update_update(@linear msg: Msg, @linear model: Model) -> Model {
         }
 
         UpdateLog(new_line) => {
-          {
+          #{
             current_stage: cs,
             steps: s,
             is_running: ir,
-            log_output: lo + "\n" + new_line,
+            log_output: lo ++ "\n" ++ new_line,
             history_depth: h
           }
         }
 
         PopState => {
           if h > 0 {
-            {
+            #{
               current_stage: UpdateStage::RpmOstree,
               steps: s,
               is_running: false,
               log_output: "",
               history_depth: h - 1
             }
           } else {
-            {
+            #{
               current_stage: cs,
               steps: s,
               is_running: ir,