Kolmogorov-Smirnov Test for Dependently Double-Truncated Durations // Performs the Kolmogorov-Smirnov-type goodness-of- fit test for exponential duration models under independent or dependently double-truncated sampling scheme using Farlie- Gumbel-Morgenstern ('FGM') copulas, as proposed by Toparkus and Weissbach (2026) doi:10.1007/s10985-026-09722-0. Provides functions for profile maximum likelihood estimation / score equation solving, computation of the two-dimensional Kolmogorov-Smirnov test statistic over the double-truncation parallelogram, simulation of the asymptotic Gaussian process limit distribution for critical values and p-value calculation, and synthetic dataset generation.