EIP-7702 session-based automation

Every task in Opus is authorized by a signed session intent, scoped to specific contracts and actions.

Session delegation transaction:

function delegateSession(
    address sessionKey,
    uint256 validUntil,
    bytes calldata permissions
) external onlyOwner {
    // Store key with time-bound expiry
}

Tasks are only executed if the session is valid at call time.