Advance development to 0.9.0.dev0 - #67

Summary

• record the verified v0.8.1 PyPI and GitHub Release artifacts and advance main to 0.9.0.dev0
• document the release-workflow recovery without changing the immutable v0.8.1 tag
• stop requiring two historical research links that the v0.8.1 product README intentionally removed, while retaining release-pinned and reachability checks for every remaining repository link

Validation

• pytest -q tests/unit/test_pypi_release_verifier.py tests/unit/test_release_state.py tests/unit/test_packaging.py::test_release_quality_has_one_version_bound_machine_readable_record (25 passed)
• ruff check .
• ruff format --check .
• mypy src/miniverl
• python scripts/build_pypi_readme.py --check
• python scripts/release_state.py --check
• python scripts/check_markdown_links.py
• git diff --check
• frozen calculator SHA-256 remains 53fc1d4d5b7adee09618d77ad62d4086ba56b78569832d6fc7c3bcd5c2695bbc

Publication record

PyPI and workflow artifacts are byte-identical. Wheel SHA-256 is 7c2a58f900cbab71689f7b229a46b5710b4aa2cbabc42af7526e2da04d9ba93e; sdist SHA-256 is f4bf486b2427d1f37edc7b0afe0c4a4f17ad9da7fbd221b010d4c7d792698789. Both PyPI integrity records expose a Trusted Publisher attestation, and a clean public core install reports miniverl 0.8.1 with a passing core doctor.