Function run_interleaved 

pub fn run_interleaved(
    target: &HttpTarget,
    value_a: &str,
    value_b: &str,
    n_per_class: usize,
    block_size: usize,
    rng: &mut impl Rng,
    on_progress: impl FnMut(usize, usize),
) -> Result<RawSamples>

Runs n_per_class measurements for each class, interleaving them in random blocks to average out drift over time. Isolated network failures don’t abort the whole run — they’re counted and reported separately, but if the failure ratio exceeds max_failure_ratio, the run stops: timings can’t be trusted over such an unstable channel.