AIXE endpoint: /aixe/serviceproviders/update-service-provider-assignment-status
Discovery request: GET /aixe/serviceproviders/update-service-provider-assignment-status/?
Action request: POST /aixe/serviceproviders/update-service-provider-assignment-status

Purpose:
Updates a service-provider assignment workflow status.

Required fields:
BusinessKey, ServiceProviderKey, AssignmentKey, Status.

Optional fields:
None.

Rules:
Allowed statuses are Assigned, Accepted, Started, and Completed.

Response convention:
SuccessCode is SUCCESS when the operation completes. Success is true on success. Errors return SuccessCode ERROR, Success false, and a Message. Numeric database IDs are never returned.