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>

tests/AcDream.App.Tests/UI/Layout/CharacterManagementUiControllerTests.cs

@@ -386,6 +386,13 @@ public sealed class CharacterManagementUiControllerTests
         UiButton exit = environment.Button(
             CharacterManagementUiController.ExitElementId);
 
+        // Gate round 2 follow-up: the window is BIGGER than the fixed canvas
+        // (the live shape — 1920×1080 window over the 800×600 authored
+        // screen). The exit dialog centered against the raw window width and
+        // landed far right of the visible canvas center.
+        environment.Host.Width = 1920f;
+        environment.Host.Height = 1080f;
+
         exit.OnClick!();
 
         Assert.NotEqual(0u, controller.ConfirmExitDialogContext);
@@ -393,6 +400,14 @@ public sealed class CharacterManagementUiControllerTests
         Assert.Equal(
             "Are you sure you want to leave?",
             Message(dialog));
+        // The dialog's scrim + popup must live in CANVAS space: scrim spans
+        // exactly the canvas, popup centers within it.
+        Assert.Equal(800f, dialog.Root.Width);
+        Assert.Equal(600f, dialog.Root.Height);
+        UiElement popup = Assert.Single(
+            dialog.Root.Children,
+            static child => child.Visible && child.Width > 0f);
+        Assert.InRange(popup.Left + popup.Width * 0.5f, 399f, 401f);
         DialogButton(dialog, RetailConfirmationDialogView.RejectButtonId).OnClick!();
 
         Assert.Equal(0, environment.Runtime.RequestExitCalls);