- Schema: mqtt_tls + mqtt_tls_insecure flags on import + test-connection
requests; model_validator enforces insecure requires tls
- Service: _build_tls_context() using ssl.create_default_context();
logger.warning when verification disabled; tls_context plumbed into
aiomqtt.Client for both fetch_networkmap and test_mqtt_connection
- Route: passes tls flags through to service
- Frontend: TLS checkbox auto-toggles port 1883<->8883 unless user
edited; insecure checkbox disabled until TLS on, red-tinted; password
field marked autocomplete=new-password
- Tests: 7 new backend tests (TLS context build, client kwargs assertion,
router happy path, insecure-without-tls 422)