Enhance VerificationSettingsDialog: add success message for link copy action and improve button styling

FoodsharingSiegen.Server/Dialogs/VerificationSettingsDialog.razor.cs

@@ -23,6 +23,8 @@ namespace FoodsharingSiegen.Server.Dialogs
         
         private int ImageCount { get; set; } = 0;
         private bool ShowLinkPanel { get; set; } = false;
+
+        private bool CopySuccess { get; set; } = false;
         private string LinkUrl { get; set; } = string.Empty;
 
         protected override async Task OnInitializedAsync()
@@ -77,6 +79,7 @@ namespace FoodsharingSiegen.Server.Dialogs
         private async Task CopyLink()
         {
             await JS.InvokeVoidAsync("navigator.clipboard.writeText", LinkUrl);
+            CopySuccess = true;
         }
 
         private async Task ViewImagesAsync()