Generate a SIPOC table from a validated PNS. Use this skill when the user needs a high-level process summary showing Suppliers, Inputs, Process steps, Outputs, and Customers; when they ask to produce a SIPOC, create a process summary table, or generate a one-page process overview. This is a process-level input/output summary, not a stakeholder engagement register — for who is involved and how to engage them, use okhp3-stakeholder-and-role-mapping instead. Derives directly from PNS process_box and activity_sequence. Produces a sipoc.md Markdown table suitable for presentations, kickoff documents, and governance packs.