Renaming or migrating https://codeberg.org/codename #5

When it is decided (i) which organization runs the fork and (ii) which name it has, https://codeberg.org/codename needs to be renamed accordingly as well as https://codeberg.org/codename/codename.

Do not rename before the Codeberg migration is over, see

https://blog.codeberg.org/codeberg-is-moving-and-what-this-means-to-you.html

Please don't hold this back if the name is decided. We have a fixup script for renames, but I wasn't sure if there was still room for race conditions and untested edge cases which might go unnoticed. (I'd surely notice for this organization, though)

The renaming is done. There surely are some leftovers that will be discovere later but that should not be too much of a concern.

• rename the org
• edit the links to the code of conduct
• rename the code repository
• rename the branches in the code repository
• rename and rebase all branches in the code repository to match the name
• update the dev workflow to use forgejo
• fixup the website CI that had references to codename
• verify the code CI still works (to the extent that it did before)