chore(solana): add support for eip712 signatures

[xenoliss]

EIP-712 Signature Support for MCM Solana Program

This PR adds support for EIP-712 signatures on Solana using the exiting eip712sign tool. It updates the MCM program patch (invoke_signed.patch is now cb.patch) to replace the old EIP-191 message signing with EIP-712 typed structured data hashing.

EIP-712 Structure

Domain Separator

EIP712Domain(string name, string version, uint256 chainId, address verifyingContract, bytes32 salt)

Values:

• name: "ManyChainMultiSig"
• version: "1"
• chainId: Solana chain identifier (e.g., 5190648258797659666 for localnet)
• verifyingContract: address(0) (0x0000000000000000000000000000000000000000)
• salt: MCM Program ID (32 bytes)

Message Structure

RootValidation(bytes32 root, uint32 validUntil)

Fields:

• root: Merkle root of operations (bytes32)
• validUntil: Expiration timestamp (uint32)

[cb-heimdall]

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[cb-heimdall]

Review Error for josephdara-cb @ 2025-10-21 13:56:37 UTC
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