checkout branch stashing/reapplying changes

If there are still changes we currently do not allow switching branches. we should instead offer to stash/reapply these changes after checkout of the other branch. Just like `fork` allows:

<img width="517" alt="Screenshot 2024-10-23 at 11 46 47" src="https://github.com/user-attachments/assets/a2c26b50-9dd3-4af6-af23-3e263c70651c">
