fix(runtime,ui): Campaign LA gate round 2 — world name reads durably; dialogs center on the canvas

Two live-integration gaps the ef96c554 unit tests could not see:

1. World box stayed empty against ACE: ServerName (0xF7E1) arrives in the
   SAME connect batch as CharacterList, so ServerNameReceived fires during
   the handshake pump BEFORE the controller binding subscribes - the
   event-only wiring proved the state and controller but never the live
   ordering. StartCore now reads the durable WorldSession.ServerInfo after
   connect exactly like the roster (ILiveSessionOperations.GetServerInfo,
   default interface method so no fake breaks); the event remains for
   post-connect updates. Pinned by a Start-level test.

2. The exit confirmation rendered far right of the screen: all three
   retail dialog views centered against the raw window size while the
   active screen lays out in the fixed 800x600 canvas - center-of-1920
   is canvas-760, which the stretch pushes off-center. Views now center
   against UiRoot.EffectiveCanvasSize (canvas while a pre-world screen is
   active, window otherwise). Pinned by growing the window over the fixed
   canvas in the exit-dialog test and asserting the scrim spans the canvas
   with the popup centered at 400.

Runtime 1666, App 5100+6 skips, green.

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

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

@@ -129,10 +129,15 @@ internal sealed class RetailConfirmationDialogView : IRetailDialogView
 
     private void SizeAndCenter()
     {
+        // Center against the space the tree lays out in — the fixed authored
+        // canvas while a pre-world screen is active (gate round 2: centering
+        // against the raw window width put the exit dialog far right of the
+        // stretched 800x600 canvas center).
+        var space = _host.EffectiveCanvasSize;
         Root.Left = 0f;
         Root.Top = 0f;
-        Root.Width = _host.Width;
-        Root.Height = _host.Height;
+        Root.Width = space.X;
+        Root.Height = space.Y;
         _popup.Left = MathF.Round((Root.Width - _popup.Width) * 0.5f);
         _popup.Top = MathF.Round((Root.Height - _popup.Height) * 0.5f);
     }

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

@@ -150,10 +150,13 @@ internal sealed class RetailConfirmationTextInputDialogView : IRetailDialogView
 
     private void SizeAndCenter()
     {
+        // Center against the layout space (fixed canvas while a pre-world
+        // screen is active) — see RetailConfirmationDialogView.SizeAndCenter.
+        var space = _host.EffectiveCanvasSize;
         Root.Left = 0f;
         Root.Top = 0f;
-        Root.Width = _host.Width;
-        Root.Height = _host.Height;
+        Root.Width = space.X;
+        Root.Height = space.Y;
         _popup.Left = MathF.Round((Root.Width - _popup.Width) * 0.5f);
         _popup.Top = MathF.Round((Root.Height - _popup.Height) * 0.5f);
     }

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

@@ -95,10 +95,13 @@ internal sealed class RetailMessageDialogView : IRetailDialogView
 
     private void SizeAndCenter()
     {
+        // Center against the layout space (fixed canvas while a pre-world
+        // screen is active) — see RetailConfirmationDialogView.SizeAndCenter.
+        var space = _host.EffectiveCanvasSize;
         Root.Left = 0f;
         Root.Top = 0f;
-        Root.Width = _host.Width;
-        Root.Height = _host.Height;
+        Root.Width = space.X;
+        Root.Height = space.Y;
         _popup.Left = MathF.Round((Root.Width - _popup.Width) * 0.5f);
         _popup.Top = MathF.Round((Root.Height - _popup.Height) * 0.5f);
     }

src/AcDream.App/UI/UiRoot.cs

@@ -44,6 +44,19 @@ public sealed class UiRoot : UiElement
     /// </summary>
     public Vector2? FixedCanvasSize { get; set; }
 
+    /// <summary>
+    /// The coordinate space the retained tree currently lays out in: the fixed
+    /// authored canvas while one is active, else the window itself. Anything
+    /// that positions against "the screen" (dialog centering, full-screen
+    /// scrims) must use THIS — the gate-round-2 exit dialog centered against
+    /// the 1920px window while the tree lived in the 800px canvas, landing far
+    /// right of the visible screen center.
+    /// </summary>
+    public Vector2 EffectiveCanvasSize =>
+        FixedCanvasSize is { X: > 0f, Y: > 0f } canvas
+            ? canvas
+            : new Vector2(Width, Height);
+
     /// <summary>Window→canvas stretch factor; One when no fixed canvas is set.</summary>
     public Vector2 CanvasScale =>
         FixedCanvasSize is { X: > 0f, Y: > 0f } canvas && Width > 0f && Height > 0f