Refresh sanitized x402 production learnings

[EdgecaseSystems]

Summary

Refreshes the sanitized portfolio snapshot with the two CDP/x402 compatibility corrections proven after the original 2026-09-07 publication:

• split the existing x402 implementation into a retained core plus a small public compatibility boundary
• use Coinbase CDP's documented server Bearer JWT claims (aud=["cdp_service"], singular request-bound uri, no legacy iat/uris)
• bound only the payment-resource description to the current 500-character CDP compatibility limit while preserving richer product copy elsewhere
• add focused regression coverage for both facts
• add a sanitized post-publication note recording the successful controlled 0.05-USDC Base-mainnet settlement and appropriate human_review_required result

Publication boundary

No production credentials, wallet identifiers, payment capabilities, request/idempotency identifiers, D1 records, deployment identifiers, or operator-only real-money audit tooling are included. The snapshot remains disconnected from production and CI remains offline/mocked.