M5: use DB-merged runtime settings for MQTT/discovery; add MQTT test button; move Expose panel into config accordion

app/main.py

@@ -26,7 +26,7 @@ from app.api.routes.ticktick import router as ticktick_router
 from app.config import get_settings
 from app.integrations.mqtt import mqtt_manager
 from app.services.auth import AuthBootstrapError, initialize_auth_schema
-from app.services.config_page import seed_missing_config_from_bootstrap, sync_app_hostname_from_bootstrap
+from app.services.config_page import build_runtime_settings, seed_missing_config_from_bootstrap, sync_app_hostname_from_bootstrap
 from app.services.public_ip import check_public_ipv4_and_notify
 from app.services.modbus_poll import poll_all_enabled_devices, BASE_POLL_TICK_SECONDS
 from app.services.ha_discovery import publish_discovery, publish_states
@@ -74,10 +74,19 @@ def _run_scheduled_ha_state_publish() -> None:
     ``mqtt_manager.connect()`` would fire before the TCP handshake completes and
     be a no-op.  Instead, this periodic job picks it up within 60 seconds of the
     broker becoming available — retained payloads make repeated publishes harmless.
+
+    Additionally, if MQTT is configured in DB but the manager is not yet connected
+    (e.g. MQTT was enabled via UI after startup), this job attempts to connect so
+    the user does not need to restart the server.
     """
     session_local = get_session_local()
     session: Session = session_local()
     try:
+        runtime_settings = build_runtime_settings(session, get_settings())
+        # Reconnect if MQTT is configured (in DB) but not yet connected.
+        if mqtt_manager.is_configured(runtime_settings) and not mqtt_manager.is_connected:
+            logger.info("_run_scheduled_ha_state_publish: MQTT configured but not connected — attempting connect.")
+            mqtt_manager.connect(runtime_settings)
         publish_discovery(session)
         publish_states(session)
     except Exception:
@@ -140,10 +149,17 @@ async def lifespan(_: FastAPI):
     )
     scheduler.start()
 
-    # MQTT: connect if configured.
+    # MQTT: connect using DB-merged runtime settings so broker configured via UI
+    # is picked up on restart (not just from env/bootstrap settings).
     # Discovery will be published by the first run of _run_scheduled_ha_state_publish
     # (within 60 s of startup), after the async paho handshake completes.
-    mqtt_manager.connect(get_settings())
+    _startup_session_local = get_session_local()
+    _startup_session: Session = _startup_session_local()
+    try:
+        _startup_runtime_settings = build_runtime_settings(_startup_session, get_settings())
+    finally:
+        _startup_session.close()
+    mqtt_manager.connect(_startup_runtime_settings)
 
     yield