Function w4a16_gemv_batch2 

pub fn w4a16_gemv_batch2(
    gpu: &dyn GpuBackend,
    kernel: KernelHandle,
    input: DevicePtr,
    weight: &QuantizedWeight,
    output: DevicePtr,
    n: u32,
    k: u32,
    stream: u64,
) -> Result<()>

2026-09-25: w4a16_gemv for 2 contiguous rows in one pass over the weight. gemv_tc::tc_fixed_m takes the launch to the tensor-core kernel when it routes it (METRALE_W4A16_TC_WIDE); otherwise kernel runs.