v2.0.0

Per-city, per-cell surge pricing computed in the matching service from ride requests and driver positions: trailing-window demand, TTL-decayed supply, a clamped multiplier stamped on every match and persisted on the trip row, GET /pricing/{city} and /quote, and surge gauges per city. Two matching replicas with a standby and static membership so a rolling update no longer rebalances the Streams group. 43 unit tests and 13 integration tests.