feat: adjust notification list margins

Added bottom margin to notification list view to improve visual spacing
The notification list now has a bottom margin of 10 pixels to create
better visual separation from the bottom edge of the container

Log: Improved notification list spacing for better visual appearance

Influence:
1. Verify notification list displays correctly with proper spacing
2. Check that bottom margin appears consistently across different
notification counts
3. Ensure scrolling behavior remains smooth with the added margin
4. Test with various screen sizes to confirm proper spacing
5. Verify that existing notifications are not affected by the layout
change

PMS: BUG-354855

Author: caimc123456

panels/notification/center/NotifyView.qml

@@ -68,6 +68,7 @@ Control {
         boundsBehavior: Flickable.StopAtBounds
         ScrollBar.vertical: ScrollBar { }
         topMargin: 20
+        bottomMargin: 10
         leftMargin: NotifyStyle.leftMargin
         property int nextIndex: -1
         property int pendingFocusIndex: -1  // Index to focus after expand operation