- Add WeChat service for OAuth2 authentication flow
- Add WeChat routes (/api/wechat/login, /api/wechat/callback)
- Add WeChat types for login state and responses
- Update EntryQRCode component to support WeChat login
- Add WeChat config options (appId, appSecret, redirectUri)
Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>