Routing IsochronesService

Approximate reachable area around a point. POST JSON to /v1/routing with a place ({"place": "Berlin Hauptbahnhof"}) or coordinates ({"origin": [52.52, 13.405]}, {"from": [lat, lon]} or {"lat": .., "lon": ..}), plus optional minutes (default 15) and speed_kmh (default 4.5, walking). The response is a JSON object with origin, radius_m and polygon: a 24-point circle of radius speed x time. With "to": [lat, lon] it also returns straight_line_m, within_reach and estimated_minutes. It does NOT follow roads or paths: all distances are straight-line. Place names are geocoded with OpenStreetMap Nominatim (cached 24 hours).