fix: implement JCS cart-to-payment mandate binding per RFC 8785#253

chopmob-cloud wants to merge 4 commits into

google-agentic-commerce:maingoogle-agentic-commerce/AP2:mainfrom

chopmob-cloud:fix/jcs-cart-payment-binding-v3chopmob-cloud/AP2:fix/jcs-cart-payment-binding-v3Copy head branch name to clipboard