Changes in version 0.1.0 (2026-10-27)                  

  - Initial CRAN submission.
  - TTM() and TTM_linear() fit weighted GEE terminal trend models on the
    retrospective time scale; RetroJM() fits the two-stage retrospective
    joint model with multiply imputed death times.
  - get_beta_mu(), get_beta_A(), plot_beta_mu(), plot_beta_A(), and
    test_beta_slope() summarize the fitted trajectories.