When creating a git worktree, we now always fetch latest `origin/main`
and create the worktree based on that. If running `git fetch` fails, we
show an error toast with the option to base the worktree of off local
`origin/main`:

<img width="530" height="45" alt="image"
src="https://github.com/user-attachments/assets/f9ae4c05-8c2c-44f3-9c14-3c291a9d82f6"
/>


Release Notes:

- git: Always create worktrees based on latest `origin/main`