public.json: Add 'GET /routes' and 'GET /route/{name}' endpoints

The new endpoints are copied from the drop endpoints, changing 'drop'
-> 'route' and 'id' -> 'name'.

Unlike drop name (e.g. 'Dufur Will-Call'), route names aren't
particularly descriptive (e.g. 'A1') and are unlikely to mutate.
Because the names are immutable, we don't need a separate 'id' field,
and we can just treat the route's name as its identifier.