feat(ui): port retail dialog factory lifecycle

Replace the single mutable confirmation service with retail's property-backed DialogFactory model: fresh DAT roots, context ids, queue groups, priority preemption, callback/close-notice ordering, and context cancellation. Route /die, server confirmation aborts, and guarded item use through focused semantic owners.

Co-Authored-By: Codex <codex@openai.com>

src/AcDream.Core.Net/Messages/GameEvents.cs

@@ -505,6 +505,22 @@ public static class GameEvents
         catch { return null; }
     }
 
+    /// <summary>
+    /// 0x0276 CharacterConfirmationDone — server cancellation/completion of the
+    /// outstanding confirmation tuple. Retail dispatches the same type/context
+    /// pair to <c>RecvNotice_AbortConfirmationRequest</c>.
+    /// </summary>
+    public readonly record struct CharacterConfirmationDone(uint Type, uint ContextId);
+
+    public static CharacterConfirmationDone? ParseCharacterConfirmationDone(
+        ReadOnlySpan<byte> payload)
+    {
+        if (payload.Length < 8) return null;
+        return new CharacterConfirmationDone(
+            BinaryPrimitives.ReadUInt32LittleEndian(payload),
+            BinaryPrimitives.ReadUInt32LittleEndian(payload.Slice(4)));
+    }
+
     // ── Shared string reader (matches LoginRequest.ReadString16L) ───────────
 
     private static string ReadString16L(ReadOnlySpan<byte> source, ref int pos)