feat(ui): 创建共享 UI 组件包

将 web 和 desktop 的重复代码抽取到 @ai-assistant/ui 包:

- 添加可配置的 API 客户端 (configureApiClient)
- 迁移共享组件: ChatMessage, ChatInput, Sidebar, FileBrowser, ConfigPanel
- 迁移共享 hook: useChat
- 添加 responsive prop 支持响应式布局
- 更新 web/desktop 依赖并删除重复代码

packages/web/src/App.tsx

@@ -5,11 +5,15 @@
  */
 
 import { useState, useEffect, useCallback } from 'react';
-import { Sidebar } from './components/Sidebar';
+import {
+  Sidebar,
+  FileBrowser,
+  ConfigPanel,
+  listSessions,
+  createSession,
+  type Session,
+} from '@ai-assistant/ui';
 import { ChatPage } from './pages/Chat';
-import { FileBrowser } from './components/FileBrowser';
-import { ConfigPanel } from './components/ConfigPanel';
-import { listSessions, createSession, type Session } from './api/client';
 
 export function App() {
   const [currentSessionId, setCurrentSessionId] = useState<string | null>(null);
@@ -76,6 +80,7 @@ export function App() {
         currentSessionId={currentSessionId}
         onSelectSession={handleSelectSession}
         onCreateSession={handleCreateSession}
+        responsive
       />
 
       {/* 工具栏按钮 - 移动端右移避开菜单按钮 */}
@@ -126,7 +131,12 @@ export function App() {
         {/* 聊天区域 */}
         <div className={`flex-1 min-w-0 ${showFileBrowser ? 'hidden md:block md:w-1/2' : 'w-full'}`}>
           {currentSessionId ? (
-            <ChatPage key={currentSessionId} sessionId={currentSessionId} onSessionNotFound={handleSessionNotFound} />
+            <ChatPage
+              key={currentSessionId}
+              sessionId={currentSessionId}
+              onSessionNotFound={handleSessionNotFound}
+              responsive
+            />
           ) : (
             <div className="flex-1 flex items-center justify-center h-full">
               <p className="text-gray-400">Select or create a session</p>
@@ -172,7 +182,7 @@ export function App() {
       </div>
 
       {/* 配置面板 */}
-      {showConfig && <ConfigPanel onClose={() => setShowConfig(false)} />}
+      {showConfig && <ConfigPanel onClose={() => setShowConfig(false)} responsive />}
 
       {/* 移动端底部文件按钮 */}
       <button