Function moe_expert_down_act_nvfp4_grouped 

pub fn moe_expert_down_act_nvfp4_grouped(
    gpu: &dyn GpuBackend,
    kernel: KernelHandle,
    geometry: Fp8GroupedGeometry,
    act: DevicePtr,
    down: Nvfp4ExpertTables,
    output: DevicePtr,
    expert_offsets: DevicePtr,
    active_experts: DevicePtr,
    active_count: DevicePtr,
    sh_act: DevicePtr,
    sh_down: &QuantizedWeight,
    sh_down_out: DevicePtr,
    n: u32,
    k: u32,
    cap: u32,
    num_tokens: u32,
    stream: u64,
) -> Result<()>