Function svm_binary_svc_probability 

pub fn svm_binary_svc_probability(
    prob: &SvmProblem,
    param: &SvmParameter,
    cp: f64,
    cn: f64,
) -> (f64, f64)

Estimate Platt scaling parameters for a binary sub-problem.

Performs 5-fold CV internally: trains on 4 folds with class weights (cp, cn), collects decision values on the held-out fold, then fits a sigmoid via sigmoid_train.

Matches LIBSVM’s svm_binary_svc_probability.