smsncut 0.1.0

• Initial release on CRAN.
• Core SMSN distribution functions: smsn_fit, smsn_density, smsn_cdf, smsn_quantile, smsn_rdist.
• Decision-theoretic cutoff: cutoff_optimal, cutoff_youden, cutoff_risk, cutoff_phi.
• Asymptotic inference: cutoff_variance, cutoff_ci, cutoff_identifiability.
• Admissible interval tools: cutoff_admissible_interval, cutoff_boundary_check, cutoff_build_interval, cutoff_expand_interval_until_valid.
• ROC analysis: smsn_roc, smsn_auc.
• Monte Carlo simulation: mc_one_rep, mc_simulate_scenario, mc_run_all.
• smsn_fit uses Richardson extrapolation (numDeriv::hessian) for the observed Fisher information matrix, critical for accurate variance estimation.
• Implements the methodology of de Paula, Mouriño, and Dias Domingues (2026), doi:10.48550/arXiv.2605.07829.