fix: clear last known good cache entry

[wangxpych]

Summary

• remove lastKnownGood.json when running either corepack cache clean or corepack cache clear
• keep deletion scoped to Corepack-managed cache entries instead of recursively removing the configurable cache root
• cover both command aliases with regression tests

Fixes #675

Tests

• yarn build
• yarn test --run (173 passed, 1 expected failure)
• yarn lint
• yarn typecheck

[wangxpych]

Closing because I’m stepping back from maintaining this contribution. Thanks for your time.

[MikeMcC399]

https://agentscan.tools/user/wangxpych

Automation signals