Function w4a16_gemv_silu_input 

pub fn w4a16_gemv_silu_input(
    gpu: &dyn GpuBackend,
    kernel: KernelHandle,
    gate_out: DevicePtr,
    up_out: DevicePtr,
    weight: &QuantizedWeight,
    output: DevicePtr,
    n: u32,
    k: u32,
    stream: u64,
) -> Result<()>

2026-09-25: W4A16 GEMV whose activation is silu(gate_out) * up_out, computed per element from the two [k] BF16 vectors inside the kernel.