Function dequant_fp8_bf16_into 

pub fn dequant_fp8_bf16_into(
    gpu: &dyn GpuBackend,
    fp8w: &Fp8Weight,
    dst: DevicePtr,
    stream: u64,
) -> Result<()>

2026-09-25: Dequantize a block-scaled or per-row FP8 weight [N,K] to BF16 into dst, a caller-owned buffer of dequant_fp8_bf16_bytes bytes.

One kernel serves both scale layouts; the block geometry passed to it selects between them:

block-scaled block_n = block_k = 128, sk = K/128 per-row block_n = 1, block_k = K, sk = 1