Clean repo with new docker-compose.yml

[hakwerk]

When the docker-only setup is fully functional, and the images can be downloaded from a container registry, then pretty much the only thing end users would need is the final docker-compose.yml file plus some documentation.
Ideally this repo gets cleaned up completely and only contains those essentials. The current repo can be renamed to e.g. "labca-builder" for the patches, image build automation, etc. Can existing installs then convert to that builder repo?!