Full x402 endpoint audit: verifies the 402 challenge, payment fields, Bazaar discovery metadata, and the origin's discov

Full x402 endpoint audit: verifies the 402 challenge, payment fields, Bazaar discovery metadata, and the origin's discovery surfaces (llms.txt, openapi.json, .well-known/x402, discovery/resources), returning a 0-100 score, pass/warn/fail checks with evidence, and recommended fixes.