Add new endpoints for querying administrative boundaries:
- GET /boundaries/countries - List all countries with boundary data
- GET /boundaries/countries/{code}/admin1 - List provinces/states
- GET /boundaries/countries/{code}/admin2 - List municipalities
- GET /boundaries/lookup?lat=&lon= - Point-in-polygon lookup
- GET /boundaries/admin2/{id}/geojson - Get single boundary GeoJSON
- GET /boundaries/countries/{code}/admin2/geojson - Get all admin2 as GeoJSON
- GET /boundaries/stats - Get boundary statistics
Uses proper joins through country_id/admin1_id foreign keys.
