color.diff always breaks diffs

I ran a script that had `git config --global color.diff always`.  This led to no diffs being displayed anymore, for instance the changes tab only shows this:

<img width="426" height="179" alt="Image" src="https://github.com/user-attachments/assets/9e15be11-7a6b-4317-a290-0b0118bbe6f9" />
