核心业务状态机

stateDiagram-v2 [*] --> PendingPickup: 创建 PendingPickup --> PickedUp: 揽收 PickedUp --> InTransit: 发出 InTransit --> Delivering: 到站派送 Delivering --> Signed: 签收 Delivering --> Exception: 异常 Exception --> Delivering: 再投 Exception --> Returned: 退回 PendingPickup --> Cancelled: 取消

stateDiagram-v2 [*] --> Unassigned Unassigned --> PendingAccept: 指派 PendingAccept --> InProgress: 接受 PendingAccept --> Unassigned: 拒绝 InProgress --> Done: 节点完成