Prepare v2.2.12 maintenance release

[1613358894]

Summary

• Add a release consistency checker for package metadata and current release docs.
• Reduce duplicated current-version wording in docs while keeping canonical release anchors.
• Document handoff_index.md as a package navigation/operator handoff artifact.
• Harden the maintenance release checklist/process.
• Bump the release version to 2.2.12.

Validation

• python scripts/check_release_consistency.py passed.
• python -m pytest -p no:cacheprovider --basetemp .tmp_pytest_v2_2_12 -> 1006 passed.
• Wheel build passed: python -m pip wheel . --no-deps -w dist.
• Wheel smoke passed after installing dist/typetreeflow-2.2.12-py3-none-any.whl in .venv_smoke_v2_2_12:
  • typetreeflow --version
  • typetreeflow doctor
  • typetreeflow --help

Boundaries

• No changes to download strategy, selection safety, or evidence thresholds.
• No real downloads were run.
• dist/ wheel artifact was kept local as smoke evidence and is not committed.