The distance calculator always queried the rentlisting table regardless of
listing type because get_listings() defaulted to RentListing when called
without query_parameters. Added a listing_type parameter to get_listings()
and _get_model_for_query() so callers can select the correct table directly.
- Fix OSRM client to use semicolons (not commas) for source/destination
indices in /table API requests. Commas caused "Query string malformed"
errors for any batch with more than one origin.
- Add error handling in poi_distance_calculator for unreachable routing
engines (OSRM/OTP). Connection failures now log an error and skip the
mode instead of crashing the entire Celery task.