feat(circuit): publish per-day passenger count updates to planning
Add Kafka support to notify planning-service of real passenger count changes per trip/date after absence-aware recalculation. Wire a new producer template/topic for TripPassengerCountUpdatedDTO, extend TripPlanningProducerService API, and emit updates from TripShortestPathRecalculationServiceImpl using active passengers count (including zero) to keep planning slots consistent without changing assignment logic.