Operates on Subcontractors, shown in the Zuper client app as "Subcontractor" (in every industry). Subcontractors share the exact same underlying schema and endpoints as Vendors / Suppliers; they're distinguished only by the vendor_type field (SUB_CONTRACTOR here) and the /subcontractors route prefix. Returns the column/field configuration used to render this module's list view — display labels, sort/lock/edit capability, and redirect targets per field, including custom fields (scoped separately per module: VENDOR vs SUBCONTRACTOR).