Add 5 coordinators for wagon flow orchestration

[jhw-db]

Implement 5 coordinators to orchestrate complete wagon flow from arrival to parking.

Coordinators:

1. ArrivalCoordinator: Handles train arrivals and wagon unloading
2. CollectionCoordinator: Moves wagons from collection to retrofit track
3. WorkshopCoordinator: Processes wagons through retrofit bays
4. ParkingCoordinator: Moves completed wagons to parking areas
5. TransportCoordinator: Manages locomotive-based transport

Design:

• Event-driven communication via SimPy queues
• Config pattern to reduce complexity
• Each coordinator has single responsibility