janusplot 0.1.0 — first CRAN release

First CRAN release (2026-04-23)

Initial public release of janusplot. The package renders a pairwise,
asymmetric smoothed-association matrix of continuous variables, with each
cell showing the fitted spline from an mgcv generalised additive model.
Upper-triangle cells plot gam(x_j ~ s(x_i)); lower-triangle cells plot
gam(x_i ~ s(x_j)). The intentional asymmetry surfaces heteroscedasticity,
leverage, and directional non-linearity that a single scalar correlation
hides.

Public surface includes:

• janusplot() — the matrix-plot entry point, with per-cell fit / CI /
  raw-data controls, hclust-ordered variables, random-effects adjustment
  via s(g, bs = "re"), and opt-in parallel fits via future.apply.
• janusplot_data() — sibling returning the fitted-model metadata
  (EDF, F-test p, asymmetry index, shape classification) without
  rendering.
• janusplot_shape_metrics() + janusplot_shape_cutoffs() +
  janusplot_shape_hierarchy() — the 24-category shape taxonomy.
• janusplot_shape_sensitivity() + helpers — recovery-rate simulation
  over 12 ground-truth shapes × 7 sample sizes × 500 replicates, with
  the precomputed shape_sensitivity_demo dataset for quick inspection.

The remainder of NEWS.md documents pre-release development history,
retained for provenance.