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/web/src/App.tsx

@@ -21,6 +21,7 @@ export function App() {
   const [isInitializing, setIsInitializing] = useState(true);
   const [showFileBrowser, setShowFileBrowser] = useState(false);
   const [showConfig, setShowConfig] = useState(false);
+  const [sessionTitleUpdate, setSessionTitleUpdate] = useState<{ sessionId: string; name: string } | null>(null);
 
   // 初始化：加载或创建会话
   useEffect(() => {
@@ -64,6 +65,11 @@ export function App() {
     }
   }, []);
 
+  // 会话标题更新回调
+  const handleSessionUpdated = useCallback((sessionId: string, name: string) => {
+    setSessionTitleUpdate({ sessionId, name });
+  }, []);
+
   if (isInitializing) {
     return (
       <div className="h-screen flex items-center justify-center bg-gray-900">
@@ -82,6 +88,7 @@ export function App() {
         onSelectSession={handleSelectSession}
         onCreateSession={handleCreateSession}
         responsive
+        sessionTitleUpdate={sessionTitleUpdate}
       />
 
       {/* 主内容区域 */}
@@ -93,6 +100,7 @@ export function App() {
               key={currentSessionId}
               sessionId={currentSessionId}
               onSessionNotFound={handleSessionNotFound}
+              onSessionUpdated={handleSessionUpdated}
               responsive
               showFileBrowser={showFileBrowser}
               onToggleFileBrowser={() => setShowFileBrowser(!showFileBrowser)}

packages/web/src/pages/Chat.tsx

@@ -16,6 +16,7 @@ import {
 interface ChatPageProps {
   sessionId: string;
   onSessionNotFound?: () => void;
+  onSessionUpdated?: (sessionId: string, name: string) => void;
   responsive?: boolean;
   // 工具栏按钮
   showFileBrowser?: boolean;
@@ -26,6 +27,7 @@ interface ChatPageProps {
 export function ChatPage({
   sessionId,
   onSessionNotFound,
+  onSessionUpdated,
   responsive = false,
   showFileBrowser,
   onToggleFileBrowser,
@@ -44,6 +46,7 @@ export function ChatPage({
       console.error('Chat error:', error);
     },
     onSessionNotFound,
+    onSessionUpdated,
   });
 
   const messagesEndRef = useRef<HTMLDivElement>(null);