feat: 添加会话标题自动生成功能

- 后端：首次 AI 回复后自动从用户消息提取标题
- 后端：通过 WebSocket 推送 session_updated 事件
- 前端：useChat hook 处理标题更新事件
- 前端：Sidebar 组件实时更新会话标题显示

packages/ui/src/hooks/useChat.ts

@@ -11,6 +11,7 @@ interface UseChatOptions {
   sessionId: string;
   onError?: (error: Error) => void;
   onSessionNotFound?: () => void;
+  onSessionUpdated?: (sessionId: string, name: string) => void;
 }
 
 interface ChatState {
@@ -20,7 +21,7 @@ interface ChatState {
   streamingContent: string;
 }
 
-export function useChat({ sessionId, onError, onSessionNotFound }: UseChatOptions) {
+export function useChat({ sessionId, onError, onSessionNotFound, onSessionUpdated }: UseChatOptions) {
   const [state, setState] = useState<ChatState>({
     messages: [],
     isConnected: false,
@@ -38,8 +39,10 @@ export function useChat({ sessionId, onError, onSessionNotFound }: UseChatOption
   // 用 ref 存储回调，避免依赖变化导致无限循环
   const onErrorRef = useRef(onError);
   const onSessionNotFoundRef = useRef(onSessionNotFound);
+  const onSessionUpdatedRef = useRef(onSessionUpdated);
   onErrorRef.current = onError;
   onSessionNotFoundRef.current = onSessionNotFound;
+  onSessionUpdatedRef.current = onSessionUpdated;
 
   // 加载历史消息
   const loadMessages = useCallback(async () => {
@@ -134,6 +137,13 @@ export function useChat({ sessionId, onError, onSessionNotFound }: UseChatOption
             onErrorRef.current?.(new Error(message.payload?.message || 'Unknown error'));
             setState((prev) => ({ ...prev, isLoading: false, streamingContent: '' }));
             break;
+
+          case 'session_updated':
+            // 会话信息更新（如标题）
+            if (message.payload?.id && message.payload?.name) {
+              onSessionUpdatedRef.current?.(message.payload.id, message.payload.name);
+            }
+            break;
         }
       } catch {
         // 忽略解析错误