Shared task group mileage create
Prices a single driver's combined trip across several task groups once. Recomputes route mileage from the ordered task locations (plus optional start/end legs), applies the CHRT-ground rate sheet, and atomically creates an OrderGroup-anchored LineItemGroup, its mileage LineItems, and the LineItemCalculation that records how the charges were derived. The LIG is detached on create (task_group_id is None) — attach to a Statement afterwards. | authz: allowed_org_types=[provider], min_org_role=operator | (SharedTaskGroupMileageCreateForProviderPayDriverClientReq) -> (LineItemGroup1)

