fix(fslib): invalidate stale archive mounts

[cyphercodes]

What's the problem this PR addresses?

Fixes #7241.

MountFS could keep treating a path as an archive after the archive file had been replaced by a directory at the same path. Follow-up reads below that path then tried to reopen the directory as a zip archive and threw EISDIR instead of falling back to the base filesystem.

How did you fix it?

findMount now revalidates cached mount paths against the configured typeCheck. If a cached archive path no longer has the expected type, the stale cached mount is discarded and the path is remembered as a non-mount so the base filesystem handles it.

I also added a regression test that first reads from a custom-extension archive, then replaces that archive path with a directory and reads the directory file through the same ZipOpenFS instance.

Checklist

• I have read the Contributing Guide.
• I have set the packages that need to be released for my changes to be effective.
• I will check that all automated PR checks pass before the PR gets reviewed.

Tests:

yarn version check
yarn jest packages/yarnpkg-libzip/tests/ZipOpenFS.test.ts --runInBand
yarn test:lint packages/yarnpkg-fslib/sources/MountFS.ts packages/yarnpkg-libzip/tests/ZipOpenFS.test.ts
yarn typecheck:all
git diff --check