Returns the owner address of an ERC-721 token on Ethereum mainnet. Takes token (contract address, 0x plus 40 hex) and id (decimal token id).

GET https://ari001.tailb4ac3a.ts.net/v1/ventures/x402_eth_reads_v1/eth_mainnet_erc721_ownerof. Same payment terms as that HTTP route. Call once with no payment. The result is the payment terms. Retry the same call with the signed payment at _meta["x402/payment"]. Measured output: {"chain": "base", "method": "ownerOf", "ok": true, "result": {"id": "5256424", "owner": "0x456979e89917f4dc1e86662fcdfd4c9766c6684d", "token": "0xa990c6a764b73bf43cee5bb40339c3322fb9d55f"}, "service": "x402_chain_reads_v1.base_erc721_ownerof"}