新增：首页 Feed 接入真实数据——四态/尾部三态/聚合曝光埋点，社区 demo 消亡第一页（T3-14）

- home_page Feed segment 改接 CommunityController：骨架屏首载、空态 CTA、
  错误横幅重试、下拉刷新（失败保留旧列表 + SnackBar）、触底游标翻页
  （失败态只走显式重试，不随滚动风暴自动重打）
- PostCard 三形态（单图通栏 4:3 / 多图折叠封面 +N 角标 / 纯文字 6 行）+
  PostMediaGrid（列数规则 + ink 80% scrim 精算）+ LikeButton（error 族修订
  Colors.red，T3-14 纯展示禁用态，ToggleSync 接线留 T3-15/16）+ FeedSkeleton
  （呼吸动效尊重减弱动态设置）；降级作者统一「宠友」占位
- SignedNetworkImage：预签名 URL 缓存 key 剥离 X-Amz-* 签名参数，
  RemoteImage 全仓换用（同图不同签名命中同一缓存条目）
- feed 域埋点：feed_viewed 聚合曝光（浏览段开/结算于切 Tab、切分段、
  退后台、销毁；≥50% 可见 ≥500ms 段内按帖去重，postId 不上报）+
  feed_load_failed（refresh/load_more 双路，会话失效不报）
- integration_test/feed_live_test.dart：compose 六容器 Linux 桌面真链路
  实测入口（PATBOND_FEED_LIVE=1 门控，默认跳过）
- 测试 379 → 421（+42）：四态/尾部三态/翻页不丢不重/降级作者/曝光结算
  时机/缓存 key/事件属性全覆盖；analyze 0，format 无 diff

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

pubspec.lock

@@ -174,6 +174,11 @@ packages:
     description: flutter
     source: sdk
     version: "0.0.0"
+  flutter_driver:
+    dependency: transitive
+    description: flutter
+    source: sdk
+    version: "0.0.0"
   flutter_image_compress:
     dependency: "direct main"
     description:
@@ -296,6 +301,11 @@ packages:
     description: flutter
     source: sdk
     version: "0.0.0"
+  fuchsia_remote_debug_protocol:
+    dependency: transitive
+    description: flutter
+    source: sdk
+    version: "0.0.0"
   hooks:
     dependency: transitive
     description:
@@ -384,6 +394,11 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "0.2.2"
+  integration_test:
+    dependency: "direct dev"
+    description: flutter
+    source: sdk
+    version: "0.0.0"
   jni:
     dependency: transitive
     description:
@@ -584,6 +599,14 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "2.1.8"
+  process:
+    dependency: transitive
+    description:
+      name: process
+      sha256: "4242ba3508d37e01808bdf71ad1d5bb93a8d671bf2e7450e6b1b353fb0808891"
+      url: "https://pub.dev"
+    source: hosted
+    version: "5.0.6"
   pub_semver:
     dependency: transitive
     description:
@@ -693,6 +716,14 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "1.4.1"
+  sync_http:
+    dependency: transitive
+    description:
+      name: sync_http
+      sha256: "7f0cd72eca000d2e026bcd6f990b81d0ca06022ef4e32fb257b30d3d1014a961"
+      url: "https://pub.dev"
+    source: hosted
+    version: "0.3.1"
   term_glyph:
     dependency: transitive
     description:
@@ -749,6 +780,14 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "1.1.1"
+  webdriver:
+    dependency: transitive
+    description:
+      name: webdriver
+      sha256: "2f3a14ca026957870cfd9c635b83507e0e51d8091568e90129fbf805aba7cade"
+      url: "https://pub.dev"
+    source: hosted
+    version: "3.1.0"
   win32:
     dependency: transitive
     description: