Add Tencent Cloud Text Moderation System (TMS) as a fallback moderation
service when OpenAI is unavailable or returns an error. The service
now checks OpenAI first, and falls back to Tencent TMS if it fails,
providing better reliability for content moderation.
Features:
- New Tencent TMS configuration in config.yaml with environment variable overrides
- New tencent package in internal/pkg/tencent/ with TMS client implementation
- PostAIService now uses dual moderation with OpenAI primary and Tencent fallback
- Strict mode configuration passed to PostAIService for consistent behavior
BREAKING CHANGE: NewPostAIService now requires tencentClient and strictMode
parameters - update wire configuration accordingly.
