Function onSyncDestroy

onSyncDestroy(callback: SyncDestroyCallback): () => void
Register a callback that fires when a remote syncDestroy event is received. The callback receives the guid and the resolved Object3D (or null if not found in the scene). The callback fires before the object is destroyed, so you can still access its state.
Parameters
- callback: SyncDestroyCallback
  Called with the guid and the Object3D about to be destroyed
Returns () => void
An unsubscribe function
Example
```
const unsub = onSyncDestroy((guid, obj) => {
  console.log("Remote object destroyed:", guid, obj?.name);
});
// later: unsub();
```