Review code and update to latest cookiecutter in handbook

[jpmckinney]

From Slack

a generic tool that takes a mapping file and flattened data and transforms it to OCDS
see if we can start recommending it to partners
can add as an option in the standard documentation

cc @yolile

• Read documentation and check that it all works as documented
• Update ruff configuration (pyproject.toml, .pre-commit-config.yaml) and fix any lints
• Add type annotations to fix mypy warnings/errors
• Add missing .github files (and check other root files)