fix(ui): #375 residual — activate the Configure Keyboard screen's own tab control

The gate-3 screenshot flight showed the keyboard list still rendering as
overlapping text after the string-resolver + parked-prototype fixes: all
SIX ActionClass pages were visible simultaneously (six stacked ListBoxes
— 'EmotesterSettings' is the Emote and CharacterSettings pages
interleaved) with six dead tab buttons above them. Root cause: OP8's
Bind built every page's rows but never called ActivateTabBehavior() on
the screen's own Type-8 tab host (0x1000049B), so no authored click
bindings were wired and no default-entry switch ran. The authored table
marks Movement (0x1000049D) IsDefault=true — activation now performs the
same default switch OptionsPanelController runs on ITS host, hiding the
other five pages and making the six tabs live.

Regressed by Bind_ActivatesTheTabControl_MovementDefaultShown_OtherPagesHidden
(fixture-driven: BehaviorActive, Movement visible, five pages hidden,
SwitchTo flips exclusivity).

Full Release suite: 13,087 passed / 4 skipped / 0 failed.

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

src/AcDream.App/UI/Layout/KeyboardConfigController.cs

@@ -161,6 +161,11 @@ public sealed class KeyboardConfigController
     private const int HeaderTemplateIndex = 0;
     private const int RowTemplateIndex = 1;
 
+    /// <summary>The screen's own Type-8 tab control hosting the six ActionClass
+    /// pages (class doc §"Six ActionClass list boxes"). Its authored tab table
+    /// (dat property 0x2E) marks Movement (0x1000049D) as the default entry.</summary>
+    private const uint TabHostElementId = 0x1000049Bu;
+
     // The row template's 3 key-button children, in "Mapping 1/2/3" column order.
     private static readonly uint[] KeyButtonIds = { 0x10000030u, 0x10000031u, 0x10000032u };
 
@@ -291,6 +296,25 @@ public sealed class KeyboardConfigController
 
         WireScreenButtons(layout, controller, bindings);
 
+        // Gate-2 screenshot finding (#375 residual): OP8 built all six pages
+        // but never ACTIVATED the screen's own tab control, so every page
+        // stayed Visible simultaneously — six stacked ListBoxes reading as
+        // "overlapping text", with six dead tab buttons above them.
+        // ActivateTabBehavior wires the authored tab clicks and performs the
+        // authored default-entry switch (Movement, IsDefault=true in the DAT
+        // table), hiding the other five pages — the exact same call
+        // OptionsPanelController makes on ITS Type-8 host at construction.
+        if (layout.FindElement(TabHostElementId) is UiTabPanel tabHost)
+        {
+            tabHost.ActivateTabBehavior();
+        }
+        else
+        {
+            Console.WriteLine(
+                $"[D.2b] KeyboardConfigController: tab host 0x{TabHostElementId:X8} not found "
+                + "(or not a UiTabPanel) — all six ActionClass pages will render stacked.");
+        }
+
         return controller;
     }