Add SystemEvent model, TelemetryService, /api/v1 telemetry endpoints, and
a /telemetry UI page. Instrument audit, notification, webhook, backup,
deployment, and monitoring paths. Add correlation_id to Notification,
EventDelivery, and DeploymentJob so related events can be grouped.
- 18 backend tests added and passing
- Frontend production build clean
- Add pluggable queue bus with SQLAlchemy backend (Redis-ready interface)
- Models: QueueGroup, Queue, QueueMessage with retries, visibility timeout,
delayed delivery, priority ordering, and dead-letter handling
- REST API at /api/v1/queue for groups, queues, messages, and stats
- Plugin SDK: from app.plugins_sdk import queue
- Operations UI page with group/queue/message management and send-message form
- Migrate webhook deliveries from raw threading.Thread to the queue bus
- Add webhook consumer with retry/dead-letter support
- Migration 022_queue_bus and backend tests