Walking distance/duration from one origin to many destinations (JSON body variant)

Identical handler and response to the GET, with the inputs in a JSON body. The body form additionally accepts dests as an array of <lat>,<lng> strings.

Proxy over the box-local OSRM instance (foot profile): one origin, up to 300 destinations, walking distance (m) and duration (s) per destination, 1 decimal. Only in-bounds destinations are sent to OSRM; out-of-bounds ones come back as null at their original index. null also marks a destination OSRM could not route.

Caching. Redis routing:table:foot:<sha1> keyed on the origin and the ORIGINAL destination list (order and out-of-bounds entries included, coordinates quantised to 5 dp ≈ 1 m), 30-day TTL; a hit is returned with cached: true.

CORS is open (*) on this router and OPTIONS answers 200. Auth: token header or ?token=; errors are always real status codes with JSON bodies (no X-RES-API-Version needed). GET /res_api/routing/health is the token-free OSRM probe.