Function calculate_offset_delay 

pub fn calculate_offset_delay(
    t1: &NtpTimestamp,
    t2: &NtpTimestamp,
    t3: &NtpTimestamp,
    t4: &NtpTimestamp,
) -> NtpMeasurement

Calculate clock offset and round-trip delay from NTP timestamps.

Using the standard NTP formulas (all in milliseconds):

• offset = ((t2 - t1) + (t3 - t4)) / 2
• delay = (t4 - t1) - (t3 - t2)

Where:

• t1 = client transmit time (origin)
• t2 = server receive time
• t3 = server transmit time
• t4 = client receive time