Purchase Order Row level location now available

Purchase order rows now support per-row location_id for multi-location receiving

Purchase order rows now expose a location_id field, letting you assign a destination location to individual rows rather than only to the purchase order as a whole.

Previously, every row on a purchase order inherited the order-level location and could only be received into that single location. Going forward, each row can specify its own location_id at create, update, and receive time, enabling a single purchase order to deliver stock into multiple locations.

This applies to endpoints that create, update, filter, or return purchase order rows, and to the receive endpoint:

GET /purchase_order_rows also accepts location_id as a query filter to list rows for a specific location. On PATCH /purchase_order_rows/{id}, location_id is updatable only while received_date is null, in line with the other editable fields on a row.