Function w4a16_gemv_batch3 

pub fn w4a16_gemv_batch3(
    gpu: &dyn GpuBackend,
    kernel: KernelHandle,
    input: DevicePtr,
    weight: &QuantizedWeight,
    output: DevicePtr,
    n: u32,
    k: u32,
    stream: u64,
) -> Result<()>

2026-09-25: w4a16_gemv_batch2 for 3 rows.