dev: implement proxy creds

CarManagerV3/Forms/MainForm.cs

@@ -13,6 +13,13 @@ namespace CarManagerV3
         List<Car> cars = new List<Car>();
         string filepath = "";
 
+        public static MainForm GetMainForm()
+        {
+            // This is a singleton pattern to ensure only one instance of MainForm exists.
+            // If you need to access the MainForm instance, you can use this method.
+            return Application.OpenForms.OfType<MainForm>().FirstOrDefault() ?? new MainForm();
+        }
+
         public MainForm(string pathToOpen = "")
         {
             InitializeComponent();