Function budgeted_maxsim 

pub fn budgeted_maxsim(
    query: &[Vec<f32>],
    doc: &[Vec<f32>],
    budget: u8,
    metric: DistanceMetric,
) -> f32

Budgeted MaxSim: only uses the first budget query vectors (Matryoshka ordering). When budget equals or exceeds query.len() this is equivalent to maxsim.

Returns 0.0 if either side is empty or budget is 0.