chore: allow Claude to run test and lint commands by default and gitignore local settings

[unnawut]

🗒️ Description

1. Allow a couple of test and lint commands that we expect the machine (and humans too) to run many many times while coding this repo
2. Gitignore settings.local.json since this file is user-specific

🔗 Related Issues or PRs

✅ Checklist

• Ran tox checks to avoid unnecessary CI fails:

  uvx tox

• Considered adding appropriate tests for the changes.
• Considered updating the online docs in the ./docs/ directory.