Ethereum mainnet eth_chainId: takes no query parameters and returns the chain id the node reports.

GET https://ari001.tailb4ac3a.ts.net/v1/ventures/x402_chain_reads_v1/eth_chainid. 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": "ethereum", "hex": "0x1", "method": "eth_chainId", "ok": true, "result": 1, "service": "x402_chain_reads_v1.eth_chainid"}