lillardhaz 1.0.0

• Initial release. Fits two-equation simultaneous hazard/probit models (probit, log-normal, or piecewise-Gompertz equations) linked by a Gaussian-copula correlation, via fit_lillardhaz().
• print, summary, and predict S3 methods for "lillardhaz" objects.
• Verified by simulation against known parameters for every eq1×eq2 combination, correlated and independent (corr = FALSE).