Mark orphaned/archived projects

Projects without an active maintainer should be marked on the https://gothenburgbitfactory.org/ website.
E.g.

* Add a badge to the project tile on the front page
* Add a info box on top of the respective project pages (like on https://gothenburgbitfactory.org/taskd/docs/)

This should be controllable via the front matter or an entry in the project data in the [data directory|https://github.com/GothenburgBitFactory/GothenburgBitFactory.github.io/tree/main/data]