新增评论通知功能：MCP工具 + REST端点 + 前端通知面板

- 新增 xhs_get_comment_notifications / xhs_reply_notification MCP工具
- 通知获取前先读取首页未读小红点数字，无未读则直接返回空，避免重复处理
- 新增 REST 端点 GET /notifications/comments 和 POST /notifications/reply
- 前端小红书页面新增「通知」按钮和 NotificationPanel slide-over 组件
- 通知面板支持查看评论通知列表和行内回复

web/src/pages/XiaohongshuPage.tsx

@@ -8,6 +8,7 @@ import { FeedGrid } from '@/components/feed/FeedGrid';
 import { FeedDetail } from '@/components/feed/FeedDetail';
 import { UserCard } from '@/components/feed/UserCard';
 import { PublishModal } from '@/components/feed/PublishModal';
+import { NotificationPanel } from '@/components/feed/NotificationPanel';
 import { useAuth } from '@/context/AuthContext';
 import { useToast } from '@/context/ToastContext';
 import { useLoginStatus } from '@/hooks/useLoginStatus';
@@ -136,6 +137,7 @@ export function XiaohongshuPage() {
   const [selectedFeed, setSelectedFeed] = useState<{ id: string; xsecToken: string } | null>(null);
   const [userView, setUserView] = useState<{ userId: string; xsecToken: string } | null>(null);
   const [publishOpen, setPublishOpen] = useState(false);
+  const [notificationOpen, setNotificationOpen] = useState(false);
 
   const loadFeed = useCallback(async () => {
     setFeedsLoading(true);
@@ -231,6 +233,9 @@ export function XiaohongshuPage() {
             <Button size="sm" variant="secondary" onClick={() => setPublishOpen(true)}>
               发布
             </Button>
+            <Button size="sm" variant="ghost" onClick={() => setNotificationOpen(true)}>
+              通知
+            </Button>
           </div>
         )}
 
@@ -364,6 +369,9 @@ export function XiaohongshuPage() {
       {/* ── Publish modal ── */}
       {publishOpen && <PublishModal onClose={() => setPublishOpen(false)} />}
 
+      {/* ── Notification panel ── */}
+      {notificationOpen && <NotificationPanel onClose={() => setNotificationOpen(false)} />}
+
       {/* ── User profile slide-over ── */}
       {userView && (
         <div className="fixed inset-0 z-50 flex">