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.Runtime/Session/LiveSessionController.cs

@@ -172,6 +172,16 @@ public interface ILiveSessionOperations
     WorldSession CreateSession(IPEndPoint endpoint);
     void Connect(WorldSession session, string user, string password);
     CharacterList.Parsed? GetCharacters(WorldSession session);
+    /// <summary>
+    /// Campaign LA gate round 2 (world-name live fix): ACE sends ServerName
+    /// (0xF7E1) in the SAME connect-response batch as CharacterList, so the
+    /// <c>ServerNameReceived</c> event fires during the handshake pump —
+    /// BEFORE the controller's binding subscribes. The durable
+    /// <see cref="WorldSession.ServerInfo"/> field is therefore read
+    /// synchronously after Connect, exactly like <see cref="GetCharacters"/>
+    /// reads the durable roster; the event remains for post-connect updates.
+    /// </summary>
+    ServerName.Parsed? GetServerInfo(WorldSession session) => session.ServerInfo;
     void StartCharacterSelectionReceive(WorldSession session) =>
         session.StartCharacterSelectionReceive();
     void EnterWorld(WorldSession session, int activeCharacterIndex);
@@ -753,6 +763,14 @@ public sealed class LiveSessionController
                     return new LiveSessionStartResult(LiveSessionStartStatus.Deferred);
             }
 
+            // World name arrives in the SAME connect batch as CharacterList,
+            // during the handshake pump — before the binding's
+            // ServerNameReceived subscription exists — so the durable field is
+            // read here exactly like the roster above (gate-round-2 live fix:
+            // the event-only wiring left the World box empty against ACE).
+            if (_operations.GetServerInfo(session) is { } serverInfo)
+                CharacterSelectionState.ApplyWorldName(serverInfo.WorldName);
+
             // Campaign LA slice LA2: the probe short-circuit lands here —
             // only after a real CharacterList was returned and its roster was
             // reported, before TrySelectCharacter ever runs. A missing