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. Supports activate, send_email, send_sms, and delete. Activate/email are processed asynchronously by a background worker. Delete skips (and reports back) any record that is a favorite supplier or set as a product's preferred vendor.