post
https://api.testnet.rise.trade/v1/orders/cancel
Cancel resting order on-chain. Gas sponsored by API service.
Signature: Signer signs VerifySignature with hash = keccak256(abi.encode(cancelData))
Cancel Data Encoding (32 bytes):
bytes[0:8] = marketId (uint64, big-endian)
bytes[8:32] = orderId (uint192, big-endian, right-aligned)