Function conv1d_update 

pub fn conv1d_update(
    gpu: &dyn GpuBackend,
    kernel: KernelHandle,
    conv_state: DevicePtr,
    input: DevicePtr,
    weight: &DenseWeight,
    output: DevicePtr,
    d_inner: u32,
    d_conv: u32,
    batch_size: u32,
    stream: u64,
) -> Result<()>

2026-09-25: Causal conv1d update + SiLU for one decode token per sequence (causal_conv1d_update). conv_state, input and output are contiguous per sequence: [batch, d_inner, d_conv], [batch, d_inner], [batch, d_inner].