Function process_jacobian_generic 

pub fn process_jacobian_generic<M: AssemblyBackend>(
    jacobian: &M::Jacobian,
    jacobi_scaling: &mut Option<Vec<f64>>,
    iteration: usize,
) -> Result<M::Jacobian, OptimizerError>

Process Jacobian with Jacobi scaling (generic over assembly mode).

On iteration == 0, computes the scaling factors and stores them. On subsequent iterations, reuses the cached scaling.