Fix app auto-navigating to Updates when a toast is shown

src/UniGetUI.Avalonia/Infrastructure/WindowsAppNotificationBridge.cs

@@ -275,11 +275,9 @@
             string launchArg = BuildLaunchArgument(launchAction);
             if (Win32ToastNotifier.Show(title, message, launchArg))
             {
-                // When the app is already running, raise activation immediately so the
-                // in-process handler fires; a subsequent toast click routes through the
-                // single-instance redirector on launch via TryParseToastLaunchArgument.
-                if (MainWindow.Instance is not null)
-                    RaiseActivation(launchAction);
+                // Show-only: the launch action fires only when the user clicks the toast, routed via
+                // the unigetui:// deep-link through the single-instance handler. Raising it on show
+                // would navigate the app on its own (e.g. yank to Updates the moment updates load).
                 return true;
             }
         }
@@ -301,6 +299,6 @@
         return true;
     }
 
     private static string BuildLaunchArgument(string action)
         => $"unigetui://{action}";
 }