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
The Go module name has been changed from `carrot_bbs` to `with_you`, which requires
all import paths to be updated throughout the codebase and by external consumers.
BREAKING CHANGE: Module name changed from carrot_bbs to with_you. All imports
and dependencies must be updated from carrot_bbs/* to with_you/*.