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/stores/utils/requestDedupe.ts

@@ -0,0 +1,58 @@
+import type { StoreApi } from 'zustand';
+
+export interface PendingRequestsSlice {
+  pendingRequests: Map<string, Promise<any>>;
+  getPendingRequest: <T>(key: string) => Promise<T> | undefined;
+  setPendingRequest: <T>(key: string, request: Promise<T>) => void;
+  deletePendingRequest: (key: string) => void;
+  clearPendingRequests: () => void;
+}
+
+export function createPendingRequestsSlice(
+  set: (partial: any) => void,
+  get: () => any
+): PendingRequestsSlice {
+  return {
+    pendingRequests: new Map(),
+
+    getPendingRequest: <T>(key: string) => {
+      return get().pendingRequests.get(key) as Promise<T> | undefined;
+    },
+
+    setPendingRequest: <T>(key: string, request: Promise<T>) => {
+      set((state: { pendingRequests: Map<string, Promise<any>> }) => {
+        const newPendingRequests = new Map(state.pendingRequests);
+        newPendingRequests.set(key, request);
+        return { pendingRequests: newPendingRequests };
+      });
+    },
+
+    deletePendingRequest: (key: string) => {
+      set((state: { pendingRequests: Map<string, Promise<any>> }) => {
+        const newPendingRequests = new Map(state.pendingRequests);
+        newPendingRequests.delete(key);
+        return { pendingRequests: newPendingRequests };
+      });
+    },
+
+    clearPendingRequests: () => {
+      set({ pendingRequests: new Map() });
+    },
+  };
+}
+
+export function createDedupe<TStore extends PendingRequestsSlice>(
+  getStore: () => StoreApi<TStore>
+) {
+  return async function dedupe<T>(key: string, fetcher: () => Promise<T>): Promise<T> {
+    const store = getStore().getState();
+    const pending = store.getPendingRequest<T>(key);
+    if (pending) return pending;
+
+    const request = fetcher().finally(() => {
+      getStore().getState().deletePendingRequest(key);
+    });
+    store.setPendingRequest(key, request);
+    return request;
+  };
+}