fix: 修复DouyinAuthClient依赖注入问题

- 在ContentModerationModule中注册DouyinAuthClient为provider
- 添加DouyinAuthClient导入声明
- 解决"getAccessToken is not a function"错误

src/content-moderation/content-moderation.module.ts

@@ -9,6 +9,7 @@ import { ContentAuditLogEntity } from './entities/content-audit-log.entity';
 
 // 适配器
 import { DouyinContentAdapter } from './adapters/douyin-content.adapter';
+import { DouyinAuthClient } from './adapters/DouYinClient';
 import { WechatContentAdapter } from './adapters/wechat-content.adapter';
 import { EnhancedWechatContentAdapter } from './adapters/enhanced-wechat-content.adapter';
 
@@ -38,6 +39,7 @@ import { ContentAuditGuard } from './guards/content-audit.guard';
   providers: [
     // 适配器实现
     DouyinContentAdapter,
+    DouyinAuthClient,
     WechatContentAdapter,
     EnhancedWechatContentAdapter,