Add FileCleanupWorker for automatic expiration of chat files with configurable retention period and batch processing. Files uploaded via `/api/v1/uploads/files` are tracked in `uploaded_files` table with expiration timestamps, then deleted from S3 and database upon expiry. Expired file URLs are injected as `"expired": true` in message responses.
Extend JPush push notification configuration with vendor-specific channel_id support (xiaomi, huawei, oppo, vivo, meizu, honor, fcm) for differentiating system vs chat notifications. Add iOS APNs thread-id grouping configuration for notification categorization.
Add JPush (极光推送) integration to enable push notifications for offline users. This includes:
- New jpush client package with API for batch push notifications
- Configuration for jpush (enabled, app_key, master_secret, production mode)
- Updated push service to send messages via JPush when users are offline
- Added PushChatMessage method with do-not-disturb checking
- Integrated push service with chat service to notify offline users of new messages
- Updated deployment workflow with JPush and related environment variables
