fix: initialization order

cmd/server/main.go

@@ -50,9 +50,13 @@ func main() {
 	if cfg.Server.Port != 0 {
 		addr = fmt.Sprintf(":%d", cfg.Server.Port)
 	}
+
+	h := &handler.Handler{DB: sqlDB, JWTSecret: cfg.Server.JWTSecret, MQTTTopic: cfg.MQTT.Topic}
+
 	// connect to MQTT broker (best-effort)
 	var mq *mqttclient.Client
 	var checker *devicecheck.Checker
+	var checkCtx context.Context
 	var checkCancel context.CancelFunc
 	if cfg.MQTT.Broker != "" {
 		mqc, err := mqttclient.Connect(cfg.MQTT)
@@ -109,8 +113,6 @@ func main() {
 	r.Use(gin.Recovery())
 	r.Use(middleware.GinLogger())
 
-	h := &handler.Handler{DB: sqlDB, JWTSecret: cfg.Server.JWTSecret, MQTTTopic: cfg.MQTT.Topic}
-
 	// Public routes
 	r.GET("/health", h.Health)
 	r.GET("/hello", h.Hello)