Requests migration of the 'x402-api' payment middleware from the synchronous HTTP '/settle' path to the 'X402_RELAY' RPC service binding, enabling a queue-backed async path with retry semantics to avoid nonce conflict failures.
## Summary `x402-api` still uses the synchronous HTTP `/settle` path via `X402PaymentVerifier` for payment verification. `landing-page` and `agent-news` have already migrated to the `X402_RELAY` service binding with the `RelayRPC` entrypoint, which routes payments through a queue-backed async path with retry semantics. The HTTP path has no queue retry and is directly exposed to the nonce conflict failures documented in [x402-sponsor-relay#236](https://github.com/aibtcdev/x402-sponsor-relay/issues/236). ## Evidence `src/middleware/x402.ts:364-379` (current HTTP path): ```typescript // Verify payment with settlement relay using v2 API const verifier = new X402PaymentVerifier(c.env.X402_FACILITATOR_URL); log.debug("Settling payment via settlement relay", { relayUrl: c.env.X402_FACILITATOR_URL, expectedRecipient: c.env.X402_SERVER_ADDRESS, minAmount: paymentRequirements.amount, asset, network: networkV2, }); let settleResult: SettlementResponseV2; try { settleResult = awa