Prepare 0.8.1 release

[douglasmonsky]

Summary

• bump package, plugin manifest, and bundled MCP runtime pin to 0.8.1
• add CHANGELOG entry for diagnostics fact table readability and sortable fact headers
• align release docs and public-package smoke commands with 0.8.1

Validation

• PYTHONPATH=src .venv/bin/python -m ruff check .
• PYTHONPATH=src .venv/bin/python -m mypy
• PYTHONPATH=src .venv/bin/python -m pytest
• PYTHONPATH=src .venv/bin/python -m pytest --cov=codex_usage_tracker --cov-report=term-missing
• PYTHONPATH=src .venv/bin/python -m compileall src
• for file in src/codex_usage_tracker/plugin_data/dashboard/dashboard*.js; do node --check ""; done
• PYTHONPATH=src .venv/bin/python scripts/check_release.py
• git diff --check
• PYTHONPATH=src .venv/bin/python -m build
• PYTHONPATH=src .venv/bin/python -m twine check dist/*
• PYTHONPATH=src .venv/bin/python scripts/check_release.py --dist
• PYTHONPATH=src .venv/bin/python scripts/smoke_installed_package.py

Local dist hashes

• f1ac4d96951d066de3a58f551c90517ed01b308b91698be0b45203210d87093c codex_usage_tracking-0.8.1-py3-none-any.whl
• 3f7e53cd14c843860b9bebf733e6e70db1c666107abda6a649783b5e130d9315 codex_usage_tracking-0.8.1.tar.gz