docs: add Frantic claim verification guide

[rohitmulani63-ops]

Summary:

• Adds a public guide explaining Frantic claim verification using a real worker-visible lifecycle example.
• Documents the contract, claim, delivery, machine check, review, and payout-ready states without exposing tokens or private payout data.
• Adds evidence and report artifacts for the Frantic Frantic bounty #17: n8n workflow calling a runx skill #39 delivery packet.

Validation:

• runx-cli 0.6.14 validation passed in a Linux container.
• Receipt: runx:receipt:sha256:ca46f4faaedd4476460e0e0c9888056799690b696fd34d4d8d31148904e781c1

I can adjust the wording or structure if you want this moved into a different docs section.