Function kda_reference_layer 

pub fn kda_reference_layer(
    hidden: &[f32],
    q: &[f32],
    k: &[f32],
    v: &[f32],
    w: &KdaWeights<'_>,
    dims: KdaDims,
    lower_bound: f32,
    rms_eps: f32,
    state: &mut [f32],
) -> Vec<f32>

2026-09-25: Reference for one KDA layer from post-conv q/k/v to the o_proj output. The short conv is not included; the golden’s inputs are post-conv.