[codex] Align Arbiter release metadata and Windows tests

[hummbl-dev]

Summary

• Align package and runtime version metadata with the current 0.6.0 alpha contract.
• Add release metadata tests and make CLI/module entry points import cleanly under isolated wheel use.
• Harden Windows-compatible test behavior around API and git-vitality paths.

Validation

• PYTHONPATH=src python -m pytest tests/ -q --ignore=tests/test_api.py -> 678 passed.
• PYTHONPATH=src python -m pytest tests/test_api.py -q -> 10 passed.
• Built wheel installed in an isolated environment and arbiter --help executed successfully.
• Peer review: Curie reviewed the branch and reported no findings.