- flake.nix pins the full toolchain (asciidoctor + pdf/epub3/diagram/
mathematical, plantuml, graphviz, jre, vale, epubcheck) via bundlerEnv
- Gemfile/Gemfile.lock/gemset.nix lock the Ruby gems; work around the
vendored mtex2MML cmake_minimum_required incompatibility
- 'nix build' produces book.pdf + book.epub; 'nix develop' gives a shell
where all existing make targets work
- CI/CD workflows now install Nix and build/lint/validate through the flake
- devcontainer uses Nix; add .envrc for direnv; document in README
Co-authored-by: Shelley <shelley@exe.dev>
