fix(chat): CH6c review fixes — opaque default, opacity-transition register clauses

BLOCKER: ChatSettings.DefaultOpacity shipped retail's base ChatInterface
value (0.5) as ONE shared global default applied to every
RetailWindowManager-registered window, not just the four floating chat
windows retail itself fades. That faded the whole out-of-box registered
UI (radar, vitals, toolbar, main chat, ...) to 50% opacity, including
several windows that can never take keyboard focus and so were stuck at
0.5 permanently. Fixed to gmMainChatUI's 1.0/1.0 override
(0x004CD0F0) instead — retail-identical opaque presentation for the 11
non-chat windows and the main chat window; only the four floating chat
windows now diverge from retail's 0.5-while-idle default, and the
Settings -> Chat transparency slider remains fully user-settable.

AP-190 reworded and gains two new decomp-verified clauses: (3) retail
eases opacity toward its target by 5% of the delta per tick
(ChatInterface::ListenToGlobalMessage @0x004F3840, armed from the focus
element-messages at @0x004F5275) where acdream snaps -- deferred, needs
a UI frame-tick hook the opacity controller doesn't have; (4) retail's
focus predicate is the chat ENTRY FIELD specifically
(ChatInterface::IsTextEntryFocused @0x004F30A0) where acdream uses
any-focusable-descendant. Both findings + the pre-existing UiMenu.cs
PushAlphaAbsolute(1f) popup bypass are folded into the window-shell
research doc's opacity section.

NITs: fixed the stale "text bypasses the alpha" comment in
UiElement.DrawSelfAndChildren (CH6c already routed DrawStringDat/
DrawString through the same ApplyAlpha chokepoint as sprites/rects);
added RetailWindowManager.WindowUnregistered + wired
RetailWindowOpacityController to detach and forget a window unregistered
while it held focus (previously only Dispose detached, leaking any
window unregistered mid-focus for the rest of the session); added
post-Dispose no-op guards to the three Set* opacity mutators; added a
DrawString (BitmapFont path) alpha regression test and a DrawStringDat
outline/background-pass alpha test (the existing tests only ever
exercised the foreground/fill pass).

Also fixes RuntimeSettingsControllerTests.SettingsViewModelSavePreserves
SectionAndTargetOrder's now-stale "target-chat-opacity:0.5:1" expectation
(caught by the full-suite run this fix requires) to match the new 1.0
default.

Campaign ledger CH6c row updated to APPROVE-WITH-FIXES.

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

src/AcDream.UI.Abstractions/Panels/Settings/ChatSettings.cs

@@ -70,7 +70,20 @@ public sealed record ChatSettings(
     // ChatOpacityLink at every setter, not by clamping here. acdream applies this
     // GLOBALLY to every RetailWindowManager-registered window (register row
     // AP-190), where retail scopes it to ChatInterface-derived windows only.
-    float DefaultOpacity = 0.5f,
+    //
+    // CH6c review fix (2026-08-10): the base ChatInterface ctor's 0.5/1.0 pair
+    // is retail-correct ONLY for the four floating chat windows —
+    // gmMainChatUI overrides to 1.0/1.0 (0x004CD0F0), and every other
+    // RetailWindowManager-registered window (radar, vitals, toolbar, ...) has
+    // no retail opacity fade at all, so applying 0.5 to them out of the box
+    // rendered the whole registered UI half-transparent forever, including
+    // several windows that can never take keyboard focus and so were
+    // PERMANENTLY stuck at 0.5. DefaultOpacity now ships 1.0, matching
+    // retail-identical opaque presentation for the 11 non-chat windows and
+    // the main chat window; the four floating chat windows lose their
+    // retail 0.5-while-idle fade by default, but the Settings → Chat
+    // transparency slider remains fully user-settable (AP-190).
+    float DefaultOpacity = 1.0f,
     float ActiveOpacity = 1.0f)
 {
     /// <summary>