Function submit_rfq_inner 

pub async fn submit_rfq_inner(
    rfq_manager: &RfqManager,
    agent_auth: &dyn AgentAuthProvider,
    rfq_id_str: &str,
    legs: &[RfqLegRequest],
    wallet_address: WalletAddress,
    nonce: u64,
    signature: &str,
    chain_id: u64,
) -> Result<RfqRecord, String>

Core RFQ submission logic shared by the REST handler and the WebSocket handler.

Validates leg count/sizes, computes the canonical legs_hash, recovers the EIP-712 signer, checks agent authorization, and delegates to RfqManager.