Function moe_weighted_sum_blend_batch2 

pub fn moe_weighted_sum_blend_batch2(
    gpu: &dyn GpuBackend,
    kernel: KernelHandle,
    output: DevicePtr,
    expert_out: DevicePtr,
    expert_weights: DevicePtr,
    shared_out: DevicePtr,
    input: DevicePtr,
    gate_weight: DevicePtr,
    hidden: u32,
    top_k: u32,
    k: u32,
    stream: u64,
) -> Result<()>

2026-09-25: moe_weighted_sum_blend for two tokens; blockIdx.y is the token.