Function build_response 

pub fn build_response(dialect: u16, guid: &[u8; 16], now: u64) -> Vec<u8> 

Build the NEGOTIATE response body (§2.2.3.1) — no security blob (clients initiate NTLMSSP in SESSION_SETUP).

The trailing 4-byte NegotiateContextOffset is emitted as 0 even for pre-3.1.1 dialects (where the spec marks it Reserved); every real-world parser expects the field’s presence.