Implementation of Logistic Box-Cox Regression

Implements a logistic Box-Cox model that adds a shape parameter to a routine logistic regression model to flexibly estimate the shape and strength of the relationship between a binary outcome and a continuous predictor, adjusting for covariates and survey weights. This model is fully described in Xing, L. et al. (2021) . This version extends the original 'lboxcox' package (1.1) with numerically stabilized likelihood/gradient calculations, vectorized data preprocessing, and a bootstrap-ensemble estimator.