feat(circuit): automatic driver assignment management for amendment replacement and splitting
- Deactivate existing TripDriverAssignment and CircuitDriverAssignment on amendment replacement
- Reassign trips for all segments during amendment splitting by inheriting existing circuit driver
- Update assignment end dates when amendment period is truncated
- Create inactive historical CircuitDriverAssignment records with stored passenger count
- Cleanup active CircuitDriverAssignment records when no active trips remain
- Handle orphaned assignments retrieval for deleted trips via CircuitDriverAssignment