feat: 添加退出登录按钮(桌面Header + 移动端"我"页面)

- Header: 桌面端右上角退出图标,带确认弹窗
- Me页面: 底部退出登录按钮,带确认弹窗

Generated with [Devin](https://devin.ai)

Co-Authored-By: Devin <158243242+devin-ai-integration[bot]@users.noreply.github.com>

web2/src/pages/Me.tsx

@@ -1,13 +1,25 @@
-/** 移动端"我"聚合页:头像占位+入口列表 */
-import { NavLink } from 'react-router-dom'
+/** 移动端"我"聚合页:头像占位+入口列表+退出 */
+import { useState } from 'react'
+import { NavLink, useNavigate } from 'react-router-dom'
 import {
   User, History, BookOpen, Settings as SettingsIcon, ChevronRight,
-  Scale, TrendingUp, Heart, ShieldCheck, FileText, Users,
+  Scale, TrendingUp, Heart, ShieldCheck, FileText, Users, LogOut,
 } from 'lucide-react'
-import { getName } from '@/lib/auth'
+import { getName, clearAuth } from '@/lib/auth'
+import {
+  Dialog, DialogContent, DialogHeader, DialogTitle, DialogDescription, DialogFooter,
+} from '@/components/ui/dialog'
+import { Button } from '@/components/ui/button'
 
 export function Me() {
+  const navigate = useNavigate()
   const name = getName()
+  const [confirmLogout, setConfirmLogout] = useState(false)
+
+  const handleLogout = () => {
+    clearAuth()
+    navigate('/login')
+  }
   const brainTrust = [
     { path: '/legal', label: '法务参谋', icon: Scale },
     { path: '/decisions', label: '经营决策', icon: TrendingUp },
@@ -61,6 +73,28 @@ export function Me() {
           ))}
         </div>
       </div>
+
+      {/* 退出登录 */}
+      <button
+        onClick={() => setConfirmLogout(true)}
+        className="flex w-full items-center justify-center gap-2 rounded-xl border border-border bg-card p-4 text-sm text-red-600 transition-colors hover:bg-red-50"
+      >
+        <LogOut className="h-4 w-4" />
+        退出登录
+      </button>
+
+      <Dialog open={confirmLogout} onOpenChange={setConfirmLogout}>
+        <DialogContent className="max-w-sm">
+          <DialogHeader>
+            <DialogTitle>退出登录</DialogTitle>
+            <DialogDescription>确定要退出当前账号吗?</DialogDescription>
+          </DialogHeader>
+          <DialogFooter>
+            <Button variant="outline" onClick={() => setConfirmLogout(false)}>取消</Button>
+            <Button variant="destructive" onClick={handleLogout}>退出</Button>
+          </DialogFooter>
+        </DialogContent>
+      </Dialog>
     </div>
   )
 }