Function moe_expert_down_act_fp8_grouped_tc_w8a8 

pub fn moe_expert_down_act_fp8_grouped_tc_w8a8(
    gpu: &dyn GpuBackend,
    kernel: KernelHandle,
    act: (DevicePtr, DevicePtr),
    down: (DevicePtr, DevicePtr),
    output: DevicePtr,
    rows: &Fp8GroupedW8a8Rows,
    sh: (DevicePtr, DevicePtr),
    sh_down: &Fp8Weight,
    sh_down_out: DevicePtr,
    n: u32,
    k: u32,
    stream: u64,
) -> Result<()>

2026-09-28: W8A8 down over the quantized SiLU products: routed rows into output by sorted position, the shared rows into sh_down_out by token, both BF16.