Function dense_gemv_fp8w_batch2 

pub fn dense_gemv_fp8w_batch2(
    gpu: &dyn GpuBackend,
    kernel: KernelHandle,
    input: DevicePtr,
    weight: &Fp8DenseWeight,
    output: DevicePtr,
    n: u32,
    k: u32,
    stream: u64,
) -> Result<()>

2026-09-25: FP8-weight GEMV for two rows in one pass over the weight: input [2, K] BF16, output [2, N] BF16, scaled by weight.row_scale. Not bit-identical to two dense_gemv_fp8w launches: the kernel adds four products to the accumulator at once, where dense_gemv_fp8w adds each product separately.