feat: add server notify

Core/notifycontroller.cpp

@@ -0,0 +1,15 @@
+#include "notifycontroller.h"
+
+NotifyController::NotifyController(QObject *parent) : QObject(parent)
+{
+
+}
+
+void NotifyController::showWarning(QString text)
+{
+    QMessageBox warning;
+    warning.setText(text);
+    warning.setIcon(QMessageBox::Warning);
+    warning.setWindowTitle(tr("Ошибка"));
+    warning.exec();
+}