Feature Request: manually edit the LLM-generated diffs via external editor

<img width="3659" height="1698" alt="Image" src="https://github.com/user-attachments/assets/ad22d0d1-f08b-4869-9e02-e6cb027bb04a" />

As shown in the figure, now we can only view the diffs; we can not accept/reject/edit the diffs via an external editor.