🐛 修复视频播放器无限循环渲染问题

## 主要修复
- 修复 FullscreenMediaModal 和 FullscreenVideoModal 中的 useEffect 循环依赖
- 重构 VideoPlayer 组件的视频属性管理逻辑
- 优化 useVideoPlayer 的初始化回调机制

## 新增功能
- 新增标签 API 支持 (lib/api/tags.ts)
- 新增内容骨架屏组件 (components/profile/content-skeleton.tsx)
- 新增返回按钮组件 (components/ui/back-button.tsx)

## 改进优化
- 优化视频播放器的性能，避免重复初始化
- 修复 useEffect 依赖项导致的无限循环更新
- 完善类型定义和 API 接口

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

components/profile/profile-screen.tsx

@@ -15,6 +15,7 @@ import { ProfileErrorState } from './profile-error-state';
 import { ProfileHeader } from './profile-header';
 import { ProfileIdentity } from './profile-identity';
 import { ProfileLoadingState } from './profile-loading-state';
+import { ContentSkeleton } from './content-skeleton';
 
 type TabKey = 'all' | 'image' | 'video';
 type BillingMode = 'monthly' | 'lifetime';
@@ -97,12 +98,15 @@ export function ProfileScreen() {
         <ContentTabs
           activeTab={activeTab}
           onChangeTab={setActiveTab}
+          isLoading={isLoading && generations.length > 0}
         />
 
         <Divider />
       </View>
 
-      {generations.length === 0 ? (
+      {isLoading && generations.length === 0 ? (
+        <ContentSkeleton />
+      ) : generations.length === 0 ? (
         <ProfileEmptyState activeTab={activeTab} />
       ) : (
         <View style={[styles.galleryContainer, { paddingHorizontal: horizontalPadding / 2 }]}>