Refactor Dockerfile into multi-stage virgin/full targets and introduce a single
flag-based image build script. Standardize image naming, remove redundant build
scripts, and update Makefile targets accordingly. CI workflows now build missing
virgin images and run root and user tests consistently across all supported
distributions.
https://chatgpt.com/share/693c29d9-9b28-800f-a549-5661c783d968