- Use context.Background() with timeout in destroySandbox/failBuild so
cleanup and DB writes survive parent context cancellation on shutdown
- Fix loop device refcount leak in FlattenRootfs when dmDevice is nil
- Replace time.After with time.NewTimer in healthcheck polling to avoid
goroutine leak when healthcheck passes early
- Capture size_bytes from CreateSnapshot/FlattenRootfs RPC responses
instead of hardcoding 0 in the templates table insert
- Avoid leaking internal error details to API clients in build handler