Fix second dialog not appearing when dialogs are shown sequentially (#1481)

* Initial plan

* Add Task.Yield() to DialogManager to fix sequential dialog display

Co-authored-by: Tyrrrz <1935960+Tyrrrz@users.noreply.github.com>

---------

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: Tyrrrz <1935960+Tyrrrz@users.noreply.github.com>

DiscordChatExporter.Gui/Framework/DialogManager.cs

@@ -38,6 +38,10 @@ public class DialogManager : IDisposable
                 }
             );
 
+            // Yield to allow DialogHost to fully reset its state before
+            // another dialog is shown (e.g. when dialogs are shown sequentially)
+            await Task.Yield();
+
             return dialog.DialogResult;
         }
     }