Function compute_batch_create_salt 

fn compute_batch_create_salt(
    process_salt: u64,
    chain_id: u64,
    nonce: u64,
    counter: u64,
) -> U256

Derive the CREATE2 salt used by --batch CREATE rewrites.

Mixes a per-inspector random seed, the chain id, the caller nonce, and a per-batch counter so that two simulations launched at the same on-chain state produce distinct salts and do not collide at the Arachnid factory.