test(ruff): cover human-readable rule selectors

[ColumbusLabs]

Summary

• add a Ruff TOML regression fixture for human-readable rule selectors
• cover extend-select, ignore, and per-file ignores
• document through the test that the current synced Ruff schema already accepts the reported selectors

The current ruff.json already contains these selector names from the Ruff schema sync in #5844, so this deliberately adds regression coverage rather than changing or loosening the schema.

Verification

• node ./cli.js check --schema-name=ruff.json
• npm run typecheck
• npm run prettier
• git diff --check

Closes #6082

[github-actions]

Thanks for the PR!

This section of the codebase is owned by @madskristensen and @hyperupcall - if they write a comment saying "LGTM" then it will be merged.