新增：帖子详情页真实数据整页替换——四态/真九宫格大图/评论区/关注双态，Feed 导航与互动全接线，demo 详情退役（T3-15/16）

- post_detail_page 整页重写：内存副本先渲染 + getPost 拉新、四态
 （loading/error+重试/ready/40403 提示后返回 Feed 并刷新）；媒体全量
  ——单图原比例（高度钳制 [0.75w,1.33w]）、多图真九宫格（D11 轮播
  弃用，本单裁定）+ InteractiveViewer 全屏大图（03 号拍板 E）
- 评论区：游标列表触底补页 + 底部输入条创建（幂等键在数据层）+
  仅本人评论渲染删除入口（40301/40404 服务端兜底）；成败埋点对
 （durationMs 取输入会话起点、attemptSeq 会话内递增）；CommentTile
  升共享组件（@ 回复前缀呈现、降级作者「宠友」占位）
- 关注双态钮（tonal ＋关注 / Outlined 已关注 + 取关确认）乐观翻转、
  回滚零动画 + SnackBar，user_followed/unfollowed(post_detail) 挂接；
  本人帖不渲染
- Feed 接通：整卡与评论钮导航详情（T3-14 占位提示移除）、点赞/收藏
  接共享 ToggleSync（详情与卡片同一实例跨页一致）、toggleError
  一次性 SnackBar 消费
- 主壳/装配：openPost 按 postId push；create demo 流不再导航已退役的
  demo 详情（发布页真实化留 T3-17）；AppState 在 post_detail/Feed 面
  消费清零
- compose 冒烟（env 门控默认跳过）：真链路发帖/点赞幂等/收藏/评论/
  删评一轮 + 断网点赞回滚（生产 ApiClient 异常链）

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

lib/app/app.dart

@@ -13,6 +13,7 @@ import 'package:patbond_flutter/features/auth/login_page.dart';
 import 'package:patbond_flutter/features/auth/session_manager.dart';
 import 'package:patbond_flutter/features/auth/splash_page.dart';
 import 'package:patbond_flutter/features/community/community_controller.dart';
+import 'package:patbond_flutter/features/community/community_interaction_analytics.dart';
 import 'package:patbond_flutter/features/community/community_repository.dart';
 import 'package:patbond_flutter/features/community/feed_analytics.dart';
 import 'package:patbond_flutter/features/main/main_shell_page.dart';
@@ -50,6 +51,7 @@ class _AppState extends State<App> {
   late final PetAnalytics petAnalytics;
   late final HealthRecordAnalytics healthRecordAnalytics;
   late final FeedAnalytics feedAnalytics;
+  late final CommunityInteractionAnalytics interactionAnalytics;
   late final SessionTracker _sessionTracker;
   late final AnalyticsService _analytics;
   late final PageViewTracker _pageViewTracker;
@@ -95,9 +97,12 @@ class _AppState extends State<App> {
     petsController = PetsController(
       repository: widget.petsRepository ?? _buildPetsRepository(),
     );
-    // T3-14：Feed segment 接线主壳（数据层 T3-12 就位）。
+    // T3-14：Feed segment 接线主壳（数据层 T3-12 就位）；T3-16 起
+    // 点赞/收藏成功埋点经 interactionAnalytics 在 controller 内上报。
+    interactionAnalytics = CommunityInteractionAnalytics(_analytics.trackEvent);
     communityController = CommunityController(
       repository: widget.communityRepository ?? _buildCommunityRepository(),
+      interactionAnalytics: interactionAnalytics,
     );
     petAnalytics = PetAnalytics(_analytics.trackEvent);
     healthRecordAnalytics = HealthRecordAnalytics(_analytics.trackEvent);
@@ -235,9 +240,11 @@ class _AppState extends State<App> {
           appState: appState,
           petsController: petsController,
           communityController: communityController,
+          currentUserId: sessionManager.userId,
           petAnalytics: petAnalytics,
           healthRecordAnalytics: healthRecordAnalytics,
           feedAnalytics: feedAnalytics,
+          interactionAnalytics: interactionAnalytics,
           pageViewTracker: _pageViewTracker,
           onLogout: authRepository.logout,
         );