Function mla_q_rope_writeback 

pub fn mla_q_rope_writeback(
    gpu: &dyn GpuBackend,
    kernel: KernelHandle,
    q_rope_direct: DevicePtr,
    q_absorbed_buf: DevicePtr,
    nq: u32,
    rope: u32,
    kv_lora: u32,
    mla_cache_dim: u32,
    stream: u64,
) -> Result<()>

2026-09-25: Write the rotated [nq, rope] Q rope parts back into q_absorbed_buf at offset kv_lora of each head’s mla_cache_dim row.