style(DialogWidget): remove backdrop filter for non-modal overlay

- Updated the non-modal dialog overlay to have no backdrop filter, enhancing visual clarity.
- Set the modal property to false in MessagesDialog to ensure proper dialog behavior.

frontend/src/components/DialogWidget.vue

@@ -195,6 +195,7 @@ export default {
 
 .dialog-overlay.non-modal {
   background: transparent;
+  backdrop-filter: none;
   pointer-events: none;
 }