config/default.py holds defaults using ~/lib/data/tfl (expanduser, so safe
to commit). app.py loads it then overlays config/local.py if present, pushing
paths into cache and circle_line modules. config/local.py is gitignored for
machine-specific absolute paths (e.g. on the server where www-data runs).
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
