Pin Loki query-frontend callback address to loopback
Under network_mode: host, frontend.address auto-detection (netutil.PrivateNetworkInterfacesWithFallback) picks up unrelated Docker bridge gateways on the host instead of loopback, causing "error notifying frontend about finished query" / connection refused on every Grafana query.
Co-Authored-By: Claude Sonnet 5 noreply@anthropic.com