feat: add socket.io events for narration broadcast

Wire narration events through the socket layer so clients receive
real-time narration updates. Server emits narration-event on creation,
narration-update when LLM text arrives, and narration-history on connect.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

shared/src/types.ts

@@ -1,4 +1,5 @@
 import type { AccessorySlot, PortraitSlot } from './constants.js';
+import type { NarrationEvent } from './narration.js';
 
 // Entity is just a numeric ID
 export type EntityId = number;
@@ -171,6 +172,9 @@ export interface ServerEvents {
   'player-joined': (data: PlayerJoined) => void;
   'player-left': (data: PlayerLeft) => void;
   'npc-recomposed': (data: { entityId: EntityId; appearance: Appearance }) => void;
+  'narration-event': (data: NarrationEvent) => void;
+  'narration-update': (data: { id: number; narration: string }) => void;
+  'narration-history': (data: NarrationEvent[]) => void;
 }
 
 // Client -> Server events