feat(src/window): migrate device monitoring to map/unmap events

Ensure monitoring starts only when the widget is shown and stops on hide, preventing timer leaks and unnecessary refreshes

src/window/notification/notification.py

@@ -367,7 +367,7 @@ def preload_notification_assets(notification):
         # Cache notification image if available
         if hasattr(notification, "image_pixbuf") and notification.image_pixbuf:
             cache_notification_image(
-                notification.id, notification.image_pixbuf, (35, 35)
+                notification.id, notification.image_pixbuf, (128, 128)
             )
 
     except Exception as e: