refactor(core): introduce EventBus and refactor store infrastructure

- Add EventBus for decoupled event-driven communication between services
- Add EventSubscriber component for centralized event handling
- Add requestDedupe utility for shared request deduplication
- Refactor api/wsService to use eventBus instead of direct router navigation
- Extract MessageMapper.toCachedMessages for consistent message mapping
- Remove deprecated BaseManager and CacheBus classes
- Improve @mention rendering with memberMap support in segment rendering
- Update hooks to use useRef instead of useState for fetch tracking

src/core/events/EventBus.ts

@@ -0,0 +1,31 @@
+type Subscriber<T> = (event: T) => void;
+
+export type AppEvent =
+  | { type: 'NAVIGATE'; payload: { path: string; params?: Record<string, any> } }
+  | { type: 'NAVIGATE_BACK' }
+  | { type: 'SHOW_VERIFICATION_MODAL' }
+  | { type: 'VIBRATE'; payload: { type: 'message' | 'group_message' | 'call' } }
+  | { type: 'SHOW_TOAST'; payload: { message: string; type: 'success' | 'error' | 'info' } }
+  | { type: 'AUTH_LOGOUT' }
+  | { type: 'AUTH_LOGIN'; payload: { userId: string } };
+
+class EventBusClass {
+  private subscribers: Set<Subscriber<AppEvent>> = new Set();
+
+  emit(event: AppEvent): void {
+    this.subscribers.forEach(subscriber => {
+      try {
+        subscriber(event);
+      } catch (error) {
+        console.error('[EventBus] Subscriber error:', error);
+      }
+    });
+  }
+
+  subscribe(subscriber: Subscriber<AppEvent>): () => void {
+    this.subscribers.add(subscriber);
+    return () => this.subscribers.delete(subscriber);
+  }
+}
+
+export const eventBus = new EventBusClass();

src/core/events/index.ts

@@ -0,0 +1,2 @@
+export { eventBus, type AppEvent } from './EventBus';
+export { useEventBus } from './useEventBus';

src/core/events/useEventBus.ts

@@ -0,0 +1,8 @@
+import { useEffect } from 'react';
+import { eventBus, AppEvent } from './EventBus';
+
+export function useEventBus(handler: (event: AppEvent) => void): void {
+  useEffect(() => {
+    return eventBus.subscribe(handler);
+  }, [handler]);
+}