Enhance OCP SDK with AP2 and MPP Protocols

[dcplatforms]

This comprehensive update transforms the Open Commerce Protocol (OCP) into a fully modern SDK for agentic and machine-to-machine payments.

Key features include:

• Agent Payments Protocol (AP2): A cryptographically secure framework using signed Intent and Cart Mandates to delegate authority to AI agents while maintaining strict budget and policy controls.
• Machine Payment Protocol (MPP): Native support for autonomous HTTP 402 'Payment Required' flows, enabling machines to settle tool-call and data-packet payments without human intervention.
• Zero Trust Security: The Secure Enclave (Vault layer) now acts as the final validator, ensuring every signed transaction matches a pre-authorized mandate's budget, expiration, and merchant whitelist.
• x402 Extension: Support for 24/7 low-latency stablecoin (USDC/PYUSD) settlements on Web3 rails.
• Developer Experience: A new ocp CLI tool to streamline agent identity creation and mandate issuance, along with modernized documentation aligned with a professional IDE aesthetic.

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PR created automatically by Jules for task 3979924792522456695 started by @dcplatforms

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