Remove the dead location_database_url / poo_database_url fields and the
location_sqlite_path / poo_sqlite_path computed properties from Settings;
drop them from the config-page payload and from .env.example. Update the
test hardcodes (test_config, test_public_ip, test_smtp) and reduce the
conftest test_database_urls fixture to the single app DB. The one-time
migration script keeps reading legacy URLs from env/CLI, independent of
Settings.
pytest 95 passed; ruff clean (pre-existing only).
tliu93