Walk-relevant POIs (school/shop/park/kindergarten/pharmacy/stops) now route
via a FOOT OSRM graph (osrm-walk service), car-relevant POIs (mall/hospital +
unknown) keep the DRIVING graph. Validation showed driving overstated
pedestrian-proximity distance — median 1.6-2.9x straight-line (#39).
- config: osrm_walk_local_url + osrm_walk_categories (frozenset, 9 walk cats)
- osrm_client_local: base_url override on get_road_distances_m (default unchanged)
- _apply_osrm_road_distances: split POIs by category, per-group OSRM call with
independent graceful fallback (one server down -> its group keeps straight-line),
in-place write-back by original index; never raises; flag-OFF byte-identical
- docker-compose: osrm-walk service (foot graph, internal, mem_limit 1.5g)
- build_osrm.sh: CAR=0 gate for foot-only refresh (doesn't touch live car graph)
- tests: per-category split, per-group fallback, asymmetric intra-group write-back
Still flag-gated (use_osrm_distances OFF) — enabling is a product decision.
Refs #39
