- snapToGraph: bbox+margin guard first (honest null = router-pending,
D-03), then 3x3 coarse-grid neighborhood (0.002 deg cells, WeakMap
memo per RoadGraph — LAW 1 lazy memoize, O(local) not O(n))
- projection in cos(lat)-scaled degree space (Pitfall 8); returned
distance is haversineM; result carries the best segment's nameId
(null for the unnamed sentinel) for plan 07's cron street-hop
- oneway-reverse edges stay snap-visible (direction is A*'s law);
gridBuildCount() instrumentation kept internal to the workspace