Multiple-Steps Step-Stress Accelerated Degradation Modeling // Implements statistical methods for multiple-steps step-stress accelerated degradation testing (SSADT) based on Wiener processes and Gamma processes as described by Pan and Balakrishnan (2010) doi:10.1080/03610918.2010.496060. Features maximum likelihood estimation (MLE), Bayesian Markov chain Monte Carlo (MCMC) sampling, Geweke convergence diagnostics, and reliability predictions under normal operating stress conditions.