Aachen Mensa CLI

Canteen menus from Studierendenwerk Aachen in your terminal - as one-shot
output for scripts, and as an interactive full-screen view.

Signing in uses RWTH's device-code flow: mensa login prints a URL that
already contains the confirmation code. Because a snap runs confined, the
credentials live in the snap's own directory rather than in ~/.config/mensa,
so this install needs a sign-in of its own.

Run snap alias aachen-mensa-cli.mensa mensa to get the short command the
documentation uses.