v2.0.0

Trip lifecycle and pickup ETA.

• New trip states arrived and in_trip between en_route and completed (Alembic 0002; the downgrade folds them back into en_route and rebuilds the enum type).
• The driver_location service advances a busy driver's trip from its position reports: first ping sets en_route, within 40 m (L1 route distance) of the pickup sets arrived, 120 m away again sets in_trip, within 40 m of the dropoff sets completed and releases the driver. Each hop is timestamped and recorded in events.
• Driver items carry a smoothed speed_mps computed from consecutive pings.
• GET /rides/{id} returns driver_position (lat, lng, heading, speed, distance to pickup, updated_at) and pickup_eta_s = route distance / observed speed + pull-over time.
• Simulated drivers drive to the pickup, wait, and continue to the dropoff; simulated riders follow the trip and only force completion after the ride window.
• Tests: full state progression through the HTTP service, ETA within 15% on a simulated grid drive, migration 0002 up and down, 75 tests total.