- Add token and encodingAESKey fields to NotificationTemplatesConfig interface
- Add UI form inputs for WeChat token and EncodingAESKey in system config page
- Add configuration constants SaTokenKey and SaEncodingAesKeyKey to SystemConfigService
- Update WeChatEventController to fetch token from database instead of hardcoded value
- Make CheckSignature method async and retrieve token from ISystemConfigService
- Update GetNotificationTemplates to include token and encodingAESKey from config
- Update SetNotificationTemplates to persist token and encodingAESKey to database
- Update mini app manifest with new appid
- Enables dynamic WeChat server configuration without code changes
