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

src/platforms/xiaohongshu/selectors.ts

@@ -187,6 +187,33 @@ export const XHS_SELECTORS = {
 
   // -- Phase 4: Interaction (Like / Favorite) --------------------------------
 
+  // -- Phase 5: Notification ------------------------------------------------
+
+  notification: {
+    /** Each notification item container. */
+    container: '.container',
+    /** User avatar link (href contains userId + xsecToken). */
+    userAvatar: 'a.user-avatar',
+    /** User name link. */
+    userName: '.user-info a',
+    /** Interaction type hint (e.g. "评论了你的笔记"). */
+    interactionHint: '.interaction-hint span:first-child',
+    /** Notification time. */
+    interactionTime: '.interaction-time',
+    /** Comment content text. */
+    interactionContent: '.interaction-content',
+    /** Note thumbnail image (parent link href contains feedId + xsecToken). */
+    extraImage: '.extra img',
+    /** Reply button to expand inline reply. */
+    replyButton: '.action-reply',
+    /** Reply textarea that appears after clicking reply. */
+    replyInput: 'textarea.comment-input',
+    /** Reply submit button. */
+    replySubmit: 'button.submit',
+    /** Unread badge on the explore page bottom menu. */
+    unreadBadge: '#global > div.main-container > div.bottom-menu > div > li.link-wrapper.bottom-channel > a > div > div',
+  },
+
   interaction: {
     /** Like button on the feed detail page. */
     likeButton: '.engage-bar-style .like-wrapper',