整合小红书页面：内联扫码登录、用户主页、移除独立登录和内容浏览页

- 新增 XiaohongshuPage：顶部搜索栏、登录用户头像/ID、退出按钮
- 未登录时内联显示二维码，无需跳转独立登录页
- 点击笔记作者可打开用户主页 slide-over（复用 UserCard）
- 修复用户主页关注/粉丝/获赞数为零：选择器从 .data-area .data-item 改为 .user-interactions > div
- 修复用户头像选择器：img.user-image（img 本身带该 class）
- backend LoginStatus 新增 avatar/userId 字段，登录状态接口返回头像和用户 ID
- 删除 LoginPage、BrowserPage，侧边栏精简为小红书单入口

src/platforms/xiaohongshu/selectors.ts

@@ -10,6 +10,10 @@ export const XHS_SELECTORS = {
     loggedInIndicator: '.user .link-wrapper .channel',
     /** The "login" button that opens the QR code modal (if not already shown). */
     loginButton: '.login-btn',
+    /** Logged-in user's avatar image in the sidebar. */
+    userAvatar: '.user .avatar img',
+    /** Logged-in user's profile link in the sidebar (href contains userId). */
+    userLink: '.user .link-wrapper a',
   },
 
   feed: {
@@ -108,8 +112,8 @@ export const XHS_SELECTORS = {
     headerContainer: '.user-info',
     /** User nickname. */
     nickname: '.user-info .user-name',
-    /** User avatar image. */
-    avatar: '.user-info .user-image img',
+    /** User avatar image (the img itself carries class user-image). */
+    avatar: '.user-info img.user-image',
     /** User bio / description text. */
     description: '.user-info .user-desc',
     /** User gender icon or text. */
@@ -117,7 +121,7 @@ export const XHS_SELECTORS = {
     /** IP location. */
     ipLocation: '.user-info .user-ip',
     /** Follower / following / interaction count elements. */
-    followCount: '.user-info .data-area .data-item',
+    followCount: '.user-info .user-interactions > div',
     /** Note count (displayed somewhere on the profile page). */
     noteCountTab: '.reds-tab-item',
     /** Individual feed items on the user profile. */