Draft: Require SALSA_TOKEN and podman login for Makefile targets

See commits for details.

This is a draft because I am not sure if it makes sense to try to automate and promote Salsa token custom registry use. For a new person joining the team and wanting to create a new package repository this may be a bit too much hoops and loops. Maybe what we really want is a very simple workflow where requesting a new repository is as easy as forking this Flight Deck, modifying a single file, and submitting a Merge Request (without having to install or run software).