Cardano Updates

also rename and move the test ssh key to make it obivous that it's no
accidential secret key left behind

- Add comprehensive integration test with mock GitHub/GitLab servers
- Test GitHub/GitLab user authentication without tokens
- Test GitHub teams and GitLab groups with token-based member fetching
- Test expired GitLab key filtering
- Test cache persistence during API outages
- Test TTL expiration and cache refresh
- Test per-user cache file isolation
- Add mock HTTP server in Crystal to simulate GitHub/GitLab APIs
- Add test SSH keys and mock API responses
- Add checks for version, help text, empty user handling, and Crystal specs
- Update nixpkgs input to nixos-unstable for integration test support
- Remove doInstallCheck flag

- Add per-Unix-user cache file support via --user flag
- Filter users to only include those matching login_user when specified
- Add URI parsing helpers to support both bare hostnames and full URLs
- Tag keys with GitHub/GitLab username instead of key title for proper filtering
- Simplify output method since files are pre-filtered during update
- Fix typo: 'tempoary' -> 'temporary'
- Change log file mode to append instead of write
- Use File.delete? instead of File.delete for graceful handling
- Bump version to 0.1.0