集成互动功能到帖子详情，删除独立互动页面

- 点赞/收藏改为纯 toggle，移除 unlike/unfavorite 参数
- 帖子详情 API 返回 isLiked/isFavorited 状态（SVG xlink:href 检测）
- 前端两个切换按钮替代原四个独立按钮
- 修复 __INITIAL_STATE__ Vue 响应式代理序列化（structuredClone + fallback）
- 修复 overlay 场景下点赞按钮误点 feed 列表元素（.last() 定位）
- 删除 InteractionsPage 及相关路由/导航

web/src/api/endpoints.ts

@@ -9,7 +9,6 @@ import type {
   HealthResponse,
   ApiResponse,
   PublishResult,
-  InteractionResult,
   CommentResult,
 } from './types';
 
@@ -101,14 +100,14 @@ export const replyComment = (data: {
     body: JSON.stringify(data),
   });
 
-export const toggleLike = (feedId: string, xsecToken: string, unlike = false) =>
-  apiFetch<ApiResponse<InteractionResult>>('/api/xhs/like', {
+export const toggleLike = (feedId: string, xsecToken: string) =>
+  apiFetch<ApiResponse<{ success: boolean; liked: boolean }>>('/api/xhs/like', {
     method: 'POST',
-    body: JSON.stringify({ feed_id: feedId, xsec_token: xsecToken, unlike }),
+    body: JSON.stringify({ feed_id: feedId, xsec_token: xsecToken }),
   });
 
-export const toggleFavorite = (feedId: string, xsecToken: string, unfavorite = false) =>
-  apiFetch<ApiResponse<InteractionResult>>('/api/xhs/favorite', {
+export const toggleFavorite = (feedId: string, xsecToken: string) =>
+  apiFetch<ApiResponse<{ success: boolean; favorited: boolean }>>('/api/xhs/favorite', {
     method: 'POST',
-    body: JSON.stringify({ feed_id: feedId, xsec_token: xsecToken, unfavorite }),
+    body: JSON.stringify({ feed_id: feedId, xsec_token: xsecToken }),
   });