feat(events,session): add React-friendly subscribe APIs and snapshot getters

Adds backwards-compatible primitives needed to consume the renderer from
React 19 hooks (useSyncExternalStore, use(), TanStack Query) without
re-architecting the event bus.

- EventDispatcher.subscribe(type, cb): () => void — unsubscriber-returning
  wrapper matching the useSyncExternalStore subscribe signature.
- CommunicationManager.subscribeMessage(eventCtor, handler): () => void —
  packet-stream equivalent.
- SessionDataManager.getUserDataSnapshot() and
  RoomSessionManager.getActiveRoomSessionSnapshot() — referentially-stable
  read-only views invalidated through new SESSION_DATA_UPDATED and
  ROOM_SESSION_UPDATED events.

All additive; existing addEventListener/removeEventListener / IRoomSession
APIs are unchanged. Bumps renderer to 2.1.0.

packages/api/src/nitro/session/IUserDataSnapshot.ts

@@ -0,0 +1,22 @@
+export interface IUserDataSnapshot
+{
+    userId: number;
+    userName: string;
+    figure: string;
+    gender: string;
+    realName: string;
+    respectsReceived: number;
+    respectsLeft: number;
+    respectsPetLeft: number;
+    canChangeName: boolean;
+    clubLevel: number;
+    securityLevel: number;
+    isAmbassador: boolean;
+    isEmailVerified: boolean;
+    isNoob: boolean;
+    isAuthenticHabbo: boolean;
+    isSystemOpen: boolean;
+    isSystemShutdown: boolean;
+    uiFlags: number;
+    tags: ReadonlyArray<string>;
+}