Function forward_batch_graph 

pub fn forward_batch_graph(
    model: &Arc<CmfModel>,
    kv_id: u64,
    layers: &[GraphLayer<'_>],
    invf: &[f32],
    h: &mut [f32],
    nh: usize,
    nkv: usize,
    hd: usize,
    rd: usize,
    hidden: usize,
    inter: usize,
    positions: &[usize],
    cap: usize,
    gemma: bool,
    eps: f32,
    k: usize,
) -> bool

Batched prefill: k contiguous positions through the whole graph in one submit (projections/FFN as GEMMs, attention/GDN looped over scratch). h is [k·hidden] in/out; positions len k. wgpu only.