Add Material to Pick List

Adds a material line item to a pick list. Returns `201 Created`. ## Identifying the material Provide the material using one of the following combinations. All invalid combinations and resolution failures return `400`. - **`materialDetailsId`** (most precise) — adds that exact material details record. If `materialId` and/or `materialVariationId` are also sent, they must match the record or the request is rejected with `400`. - **`materialId` only** — resolves the material at the pick list's source location (`fromLocation`). Succeeds only when the material has a single variation stocked there. Returns `400` if the material is not stocked at the source location, or if it has more than one variation stocked there (add `materialVariationId` to disambiguate, or pass `materialDetailsId`). - **`materialId` + `materialVariationId`** — resolves the specified variation at the source location. Returns `400` if that variation is not stocked there. `materialVariationId` must always be accompanied by `materialId`; sent on its own it returns `400`. Sending neither `materialDetailsId` nor `materialId` also returns `400`. ## When `materialVariationId` is required A catalog material can have several variations (e.g. sizes or colors) stocked at the same location, each its own material details record. `materialId` alone cannot pick between them, so it returns `400` until you either add `materialVariationId` or pass the specific `materialDetailsId`. Materials with a single variation at the source location resolve from `materialId` alone. ## Finding the materialDetailsId If you prefer to add by `materialDetailsId`, retrieve it from `GET /locations/{id}/materials` — each row's `materialDetailsId` is the value to send here. Filter that endpoint with `materialIds` to find the record(s) for a known material at the source location. Requires scope: `pick_lists:write`