POC settlement routing

POC decision. For the POC, all x402 payments, subscription and usage, are routed to the Verifiable Credential issuer (payTo = VC issuer account). Payments may use JMYR (ZTP20) or the native Zetrix token; the technical team selects the asset for the POC. Currently only a single JMYR (ZTP20) accepts[] entry is returned, native ZTX is temporarily disabled in config and re-enabling it is config-only. In a later stage, usage payments may route to the individual resource server instead.