refactor: update onBeforeDelete to match asynchronous function signature

- Modified the onBeforeDelete function to be asynchronous, allowing for better handling of pending node removals.
- This change improves the deletion logic by ensuring that node states are managed correctly before deletion occurs.

Author: CoolSpring8

src/components/DiagramView.tsx

@@ -392,7 +392,7 @@ const DiagramView = ({
 							});
 							pendingNodeRemovalsRef.current.clear();
 						}}
-						onBeforeDelete={({ nodes }) => {
+						onBeforeDelete={async ({ nodes }) => {
 							pendingNodeRemovalsRef.current = new Set(
 								nodes.map((node) => node.id),
 							);