OTel Metrics, Backup Guard, and Default Registry Init

This release improves observability and reliability across Daytona’s core infrastructure.

The API now exposes OpenTelemetry metrics and logs, enabling better performance monitoring and tracing, and providing deeper insight into system behavior and debugging.

Additional fixes ensure stable backup handling during sandbox destruction, prevent access errors through a new volume guard, and validate runner readiness during startup.

The update also introduces default backup registry initialization and refactors organization quotas to load from configuration for more predictable scaling.