EIP-712 messages as confidential requests

[ferranbt]

📝 Summary

📚 References

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• [ ] I have seen and agree to CONTRIBUTING.md

[zeroXbrock]

good first stab! so the client builds a CCRecord and encodes it into an EIP-712 payload , then signs and sends that to the eth_sendRawTransaction2 endpoint in a CCRequest2 envelope with confidentialInputs appended. I think this'll work. Just needs signature verification.