Returns channel commission entries stored specifically for the given listing (unit type).

This does not resolve account-level inheritance — it returns only listing-level stored values. Each item includes levelEntityType set to UNIT_TYPE. When no listing-level commissions exist, the response is an empty array. If unitTypeId is a sub-unit, it is remapped to the parent unit type before lookup (sub-units are not rejected with 400 on this path). PUT /unit-type/{unitTypeId} does not remap — it stores under the ID you send — so prefer the parent unit type ID when writing so GET and PUT address the same document. Use the /actual endpoint to get the commissions that currently apply based on the listing level configuration.