Operates on Vendors. In the Zuper client app this module is labeled "Vendor" for most companies, and "Supplier" for companies in the roofing industry — the API and data shape are identical either way. Vendors and Subcontractors share the exact same underlying schema and endpoints; they're distinguished only by the vendor_type field (VENDOR here) and the /vendors vs /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.