Function compute_ml_descriptors 

pub fn compute_ml_descriptors(
    elements: &[u8],
    bonds: &[(usize, usize, u8)],
    charges: &[f64],
    aromatic_atoms: &[bool],
) -> MolecularDescriptors

Compute molecular descriptors for ML property prediction.

elements: atomic numbers. bonds: (atom_i, atom_j, bond_order) list. charges: partial charges (or empty slice for default). aromatic_atoms: aromatic flags per atom (or empty slice).