Function gated_rms_norm_prefill 

pub fn gated_rms_norm_prefill(
    gpu: &dyn GpuBackend,
    kernel: KernelHandle,
    input: DevicePtr,
    gate: DevicePtr,
    weight: &DenseWeight,
    output: DevicePtr,
    heads_per_token: u32,
    head_dim: u32,
    eps: f32,
    num_actual_tokens: u32,
    input_token_stride: u32,
    gate_token_stride: u32,
    stream: u64,
) -> Result<()>

2026-09-25: Gated RMS norm of every (head, token) row of a prefill chunk in one launch. input and output rows of token t start at t * input_token_stride, and gate rows at t * gate_token_stride, both in BF16 elements.