Function validate_cnf_gpu 

pub fn validate_cnf_gpu(
    cnf: &GpuCnf,
    provider: &CudaKernelProvider,
) -> Result<()>

Validate GpuCnf CSR invariants on the GPU (fail-fast trap on invalid input).

This is used as a mandatory invariant check for GPU-native compilation paths where the host cannot safely “peek” into device-resident CNF buffers.