Fix crash when dragging rotation control in editor with both mouse buttons

Closes https://github.com/ppy/osu/issues/26325.

osu.Game/Screens/Edit/Compose/Components/SelectionBoxRotationHandle.cs

@@ -62,6 +62,9 @@ namespace osu.Game.Screens.Edit.Compose.Components
 
         protected override bool OnDragStart(DragStartEvent e)
         {
+            if (e.Button != MouseButton.Left)
+                return false;
+
             if (rotationHandler == null) return false;
 
             rotationHandler.Begin();