When asked about Windows support, I was wondering what we might have to do to get radicle-term to work…

Ditching the pager implementation, and getting rid of a lot of maintenance burden, is the big step here.

Tested on my machine, runs nicely. Please test locally before merging, especially:

• rad sync, which makes heavy use of the spinner.
• Something involving editing, like rad comment edit or rad id update --edit.
• The fact that rad patch diff and rad diff still work.

Do not actually remove rad diff, but use the user’s pager.