upgrade to newer reusable Github workflow; rename requirements files; add `ruff` linting rules; add `black` config for line length 80
+x
- transition to `pyproject.toml` config - include license (Apache-2.0) - add dev tools - add documentation config (`mkdocs` based) - turn `README.md` into a symlink to docs `index.md` - add convenience scripts for testing and linting