Function sigmoid_gate_mul_head_broadcast 

pub fn sigmoid_gate_mul_head_broadcast(
    gpu: &dyn GpuBackend,
    kernel: KernelHandle,
    input: DevicePtr,
    gate: DevicePtr,
    output: DevicePtr,
    nq: u32,
    hd: u32,
    num_tokens: u32,
    stream: u64,
) -> Result<()>

2026-09-25: output[t, h, d] = input[t, h, d] * sigmoid(gate[t, h]): one BF16 gate value per head, [num_tokens, nq], broadcast over the head’s hd elements (kernel sigmoid_gate_mul_head_broadcast).