fix: config adapters must not overwrite code-registered internal handlers

Config-loaded adapters (from gateway-config-secret.yaml) were overwriting
code-registered workflow adapter that has internal Handler for JSON-to-gRPC
translation. Now skips config adapters if serviceName already registered.

cmd/gateway/main.go

@@ -108,8 +108,12 @@ func main() {
 	}
 	_ = registry.Add(notifAdapter)
 
-	// Add other adapters from config
+	// Add other adapters from config (skip if already registered in code)
 	for _, a := range cfg.Adapters {
+		if existing := registry.Get(a.ServiceName); existing != nil {
+			log.Printf("skip config adapter '%s': already registered with internal handler", a.ServiceName)
+			continue
+		}
 		_ = registry.Add(a)
 	}
 	log.Printf("%d service adapters loaded", registry.Count())