Vega Payments API

Merchant self-serve. Work-email + password signup → verify → vega_test_ sandbox key. Get sandbox key (or Vera). Log in later for key metadata / rotate. No social login. KYB for live keys. Agentic: mint agents under Merchants/Agents, then VACP /vacp/v1/handshake + /vacp/v1/execute with X-Vega-Agent-DID + X-Vega-Signature.