ubuntu-latest maps to docker://node:20-bookworm with python3 but no pip.
Install python3-pip via apt (reuse-surface pattern), use short-SHA archive
checkout, and --break-system-packages for PEP 668. Unblocks CUST-WP-0059 T05.
Adds .forgejo/workflows/ci.yml (black/flake8/pytest) and publish-python-package.yml
(twine → forgejo PyPI), modeled on issue-core. Removes the frozen-gitea ci.yml and
publish workflows. CUST-WP-0059 T02-T04.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
