### What problem does this PR solve?
About issue #10140
In version 0.20.1, we implemented the generation of new node through
mouse drag and drop. If we could create a workflow module like in Coze,
where there is not only a dropdown menu but also an intermediate node
(placeholder node) after the drag and drop is completed, this could
improve the user experience.
### Type of change
- [x] New Feature (non-breaking change which adds functionality)