Fix monitoring PF CI lint issues

cmd/server/main.go

@@ -27,7 +27,11 @@ func main() {
 		slog.Error("db_open_failed", "error", err)
 		os.Exit(1)
 	}
-	defer app.Close()
+	defer func() {
+		if err := app.Close(); err != nil {
+			slog.Warn("app_close_failed", "error", err)
+		}
+	}()
 
 	server := &http.Server{
 		Addr:              fmt.Sprintf("%s:%d", cfg.WebHost, cfg.WebPort),