A manufacturing company wants an AI solution to accelerate supplier onboarding. The process involves collecting supplier documents, validating them against internal compliance rules, and routing approvals. The business has these constraints: the workflow logic is highly specific to their internal ERP, a vendor offers a generic onboarding SaaS agent that covers ~60% of the steps, and the company already uses Microsoft 365 Copilot broadly. Leadership asks the architect for a build-vs-buy-vs-extend recommendation that minimizes total cost of ownership while meeting the specialized requirements. Which recommendation best fits?