feat(recommend): 新增推荐频道页并恢复首页沉浸式信息流

- tab1 推荐页改为接口分类频道：频道导航可横滑，选中频道自动滚动到可视区，内容区左右滑动切换分类
- 精选频道：顶部固定高度 banner 轮播图 + 接口 tag 筛选的上新短剧横滑 + 其余短剧双列网格；其他分类三列网格
- 分类内容支持懒加载、下拉刷新与上拉分页加载
- 卡片角标文案与背景色取自接口 tag/tagColor，短剧标题统一白色
- 恢复 tab0 为沉浸式全屏视频首页及其三 inner-tab 顶导（搜索/礼物入口）
- l10n 新增原创出品、立即观看、上新、编辑精选、全N集等多语言文案

lib/core/widgets/app_root_tab.dart

@@ -7,18 +7,12 @@ import 'app_bottom_nav.dart';
 
 /// 客户端根导航的固定顺序。
 enum AppRootTab {
-  home(
-    assetPath: 'assets/icon/film_reel.png',
-    selectedAssetPath: 'assets/icon/film_reel_filled.png',
-  ),
+  home(),
   recommend(),
   following(),
   mine();
 
-  const AppRootTab({this.assetPath, this.selectedAssetPath});
-
-  final String? assetPath;
-  final String? selectedAssetPath;
+  const AppRootTab();
 }
 
 extension AppRootTabUi on AppRootTab {
@@ -30,15 +24,15 @@ extension AppRootTabUi on AppRootTab {
   };
 
   IconData get icon => switch (this) {
-    AppRootTab.home => Icons.theaters_outlined,
-    AppRootTab.recommend => Icons.smart_display_outlined,
+    AppRootTab.home => Icons.home_outlined,
+    AppRootTab.recommend => Icons.celebration_outlined,
     AppRootTab.following => Icons.bookmark_border_rounded,
     AppRootTab.mine => Icons.person_outline_rounded,
   };
 
   IconData get selectedIcon => switch (this) {
-    AppRootTab.home => Icons.theaters,
-    AppRootTab.recommend => Icons.smart_display_rounded,
+    AppRootTab.home => Icons.home_rounded,
+    AppRootTab.recommend => Icons.celebration_rounded,
     AppRootTab.following => Icons.bookmark_rounded,
     AppRootTab.mine => Icons.person_rounded,
   };
@@ -75,8 +69,6 @@ class AppRootBottomNav extends StatelessWidget {
             tabKey: tab.tabKey,
             icon: tab.icon,
             selectedIcon: tab.selectedIcon,
-            assetPath: tab.assetPath,
-            selectedAssetPath: tab.selectedAssetPath,
             label: tab.label(l10n),
             selected: tab == selected,
             onTap: () => onSelected(tab),