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/types/dto.ts

@@ -721,7 +721,7 @@ export interface SSEEvent extends WSEvent {}
  * 从消息segments中提取纯文本内容
  * 用于消息列表显示、通知等场景
  */
-export function extractTextFromSegments(segments?: MessageSegment[]): string {
+export function extractTextFromSegments(segments?: MessageSegment[], memberMap?: Map<string, { nickname: string; user_id: string }>): string {
   if (!segments || segments.length === 0) {
     return '';
   }
@@ -731,7 +731,6 @@ export function extractTextFromSegments(segments?: MessageSegment[]): string {
   for (const segment of segments) {
     switch (segment.type) {
       case 'text':
-        // 兼容 content 和 text 两种字段
         const textData = segment.data as TextSegmentData;
         result += textData.content ?? textData.text ?? '';
         break;
@@ -739,10 +738,10 @@ export function extractTextFromSegments(segments?: MessageSegment[]): string {
         const atData = segment.data as AtSegmentData;
         if (atData.user_id === 'all') {
           result += '@所有人 ';
-        } else if (atData.nickname) {
-          result += `@${atData.nickname} `;
         } else {
-          result += `@${atData.user_id} `;
+          const member = memberMap?.get(atData.user_id);
+          const displayName = member?.nickname || atData.nickname || atData.user_id;
+          result += `@${displayName} `;
         }
         break;
       case 'image':