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/desktop/src/App.tsx

@@ -2,7 +2,7 @@
  * App Component
  */
 
-import { useState, useEffect } from 'react';
+import { useState, useEffect, useCallback } from 'react';
 import {
   Sidebar,
   FileBrowser,
@@ -19,6 +19,7 @@ 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(() => {
@@ -52,6 +53,11 @@ export function App() {
     setCurrentSessionId(session.id);
   };
 
+  // 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">
@@ -69,6 +75,7 @@ export function App() {
         currentSessionId={currentSessionId}
         onSelectSession={handleSelectSession}
         onCreateSession={handleCreateSession}
+        sessionTitleUpdate={sessionTitleUpdate}
       />
 
       <div className="flex-1 flex">
@@ -78,6 +85,7 @@ export function App() {
             <ChatPage
               key={currentSessionId}
               sessionId={currentSessionId}
+              onSessionUpdated={handleSessionUpdated}
               showFileBrowser={showFileBrowser}
               onToggleFileBrowser={() => setShowFileBrowser(!showFileBrowser)}
               onOpenConfig={() => setShowConfig(true)}

packages/desktop/src/pages/Chat.tsx

@@ -15,6 +15,7 @@ import {
 
 interface ChatPageProps {
   sessionId: string;
+  onSessionUpdated?: (sessionId: string, name: string) => void;
   // 工具栏按钮
   showFileBrowser?: boolean;
   onToggleFileBrowser?: () => void;
@@ -23,6 +24,7 @@ interface ChatPageProps {
 
 export function ChatPage({
   sessionId,
+  onSessionUpdated,
   showFileBrowser,
   onToggleFileBrowser,
   onOpenConfig,
@@ -39,6 +41,7 @@ export function ChatPage({
     onError: (error) => {
       console.error('Chat error:', error);
     },
+    onSessionUpdated,
   });
 
   const messagesEndRef = useRef<HTMLDivElement>(null);