fix(chat): CH6a/b rework — grip media, retail window-id model, floaty fixture

Applies docs/research/2026-08-10-ch6ab-review-findings.md in full:

- BLOCKER 1: UiResizeGrip now carries its ElementInfo/resolve pair and
  draws its own authored DirectState media (a synthetic parameterless
  grip still draws nothing, preserving existing resize-drag tests).
  DatWidgetFactory.BuildResizeGrip threads resolve through. All seven
  live grips on the main chat window now resolve a non-zero sprite,
  restoring the visible borders/corners CH6a silently dropped.

- SHOULD-FIX 2: ChatWindowState gains BroadcastTargetWindow, a sentinel
  distinct from every real window id (0-4), fixing the bug where the
  main window's explicit-addressing branch coincided with the broadcast
  check (both were literal 0). SetFilter's main-window no-op is dropped
  — the main window's filter is now genuinely settable. ChatWindowController
  .Bind takes a ChatWindowState (the same canonical instance the floating
  windows already share) and GetTranscriptLines builds a real accept
  predicate instead of accept:null. Verified safe: ClientLocal (0x1A)
  never reaches ChatLog (AddText routes it to the SpewBox and returns),
  so nothing observable regresses.

- SHOULD-FIX 3: UiButton.SuppressSelfToggle stops the four chat-window
  indicator buttons (DAT property 0x0B=true, no retail click handler)
  from flipping their own Selected mirror on a stray click.

- SHOULD-FIX 4: generated and committed chat_floaty_2100005b.json from
  the real installed dats; added the permanent RetailLayoutFixtureGenerator
  entry. All three flagged FloatingChatWindowController assumptions
  (input field, title bar, close button) are confirmed correct against
  real data — no controller code changes needed. New finding: unlike the
  main window, ALL EIGHT floaty border/corner elements are live Type-9
  grips (the floaty's own title bar is its move handle), so a floaty
  window resizes from every edge and corner.

- SHOULD-FIX 5: register row AP-189 documents the shared-500-entry/
  200-line-tail vs retail's per-window 10,000-line scrollback depth gap.

- NITs 1-5: documented the filter-persistence-only-on-/saveautoui
  asymmetry and the reconnect-preserves-filters intent; corrected the
  research doc's modifier-mask mislabel and the "ONLY function" false
  superlative; moved WrapText off ChatWindowController onto
  ChatTranscriptRenderer, closing the circular dependency.

Full Release suite: 12,420 passed / 4 skipped / 0 failed (baseline
12,392/4/0 at 22020ef2; net +28 tests, zero regressions).

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

src/AcDream.App/UI/UiButton.cs

@@ -111,6 +111,23 @@ public sealed class UiButton : UiElement, IUiGlobalTimeListener, IUiDatStateful
     public float HotClickInitialDelay { get; }
     public float HotClickRepeatInterval { get; }
 
+    /// <summary>
+    /// Opt-out for a <see cref="ToggleBehavior"/> button whose <see cref="Selected"/>
+    /// state is a PURE MIRROR of external state (a producer other than the click
+    /// itself is the only legitimate writer — e.g. <see cref="ChatWindowController.SetIndicatorOpen"/>
+    /// mirroring a floating chat window's own visibility). CH6a/b REJECT-review
+    /// SHOULD-FIX 3: the chat-window 1-4 indicators (<c>0x10000522</c>-<c>0x10000525</c>)
+    /// carry DAT property <c>0x0B</c> (<see cref="ToggleBehavior"/>) = true, so
+    /// without this flag a click flips their Highlight/Normal art with no
+    /// underlying visibility change — the mirror lies until the next real
+    /// toggle. Retail confirms clicking these buttons does nothing
+    /// (<c>gmMainChatUI::ListenToElementMessage @0x004CDA80</c> has no case for
+    /// their element ids — see <see cref="ChatWindowController.SetIndicatorOpen"/>'s
+    /// doc). Default <see langword="false"/> — every OTHER toggle button (max/min,
+    /// checkboxes) keeps retail's normal click-toggles-itself behavior.
+    /// </summary>
+    public bool SuppressSelfToggle { get; set; }
+
     public bool Selected
     {
         get => _selected;
@@ -435,7 +452,7 @@ public sealed class UiButton : UiElement, IUiGlobalTimeListener, IUiDatStateful
                 _suppressNextClick = _hotClicking && _pointerOver;
                 _hotClicking = false;
                 _nextHotClickTime = double.NaN;
-                if (_pressed && _pointerOver && Enabled && ToggleBehavior)
+                if (_pressed && _pointerOver && Enabled && ToggleBehavior && !SuppressSelfToggle)
                     _selected = !_selected;
                 if (_pressed && Enabled)
                     OnReleased?.Invoke();