[0.2.8] - 2026-06-07

Added

• optimize(kind='mr'): new 1-D optimization model for the recency axis.
  Enforces monotone decreasing + convex constraints on the marginal recency probability R2Prob,
  then broadcasts the result across all frequency values.

• optimize(kind='mf'): new 1-D optimization model for the frequency axis.
  Enforces monotone increasing + concave constraints on the marginal frequency probability F2Prob,
  then broadcasts the result across all recency values.

• er model: empirical recency marginal probability (R2Prob) broadcast to the full RF grid.
  Computed automatically inside fit() / fit_period(); no extra call needed.

• ef model: empirical frequency marginal probability (F2Prob) broadcast to the full RF grid.
  Computed automatically inside fit() / fit_period(); no extra call needed.

• Corresponding attributes populated by optimize(kind='mr'):
  mr_probability_, mr_probability_table_, mr_probability_dict_

• Corresponding attributes populated by optimize(kind='mf'):
  mf_probability_, mf_probability_table_, mf_probability_dict_

• Corresponding attributes populated by fit() / fit_period():
  er_probability_, er_probability_table_, er_probability_dict_,
  ef_probability_, ef_probability_table_, ef_probability_dict_

• Kind alias system: long descriptive names are accepted everywhere and normalized to their
  canonical short forms via _normalize_kind().

  Alias	Canonical
  empirical	emp
  empirical_recency	er
  empirical_frequency	ef
  monotone	mono
  monotone_recency	mr
  monotone_frequency	mf
  monotone_recency_convex	mrc
  monotone_frequency_concave	mfc
  monotone_convex_concave	mcc

• plot_marginal_probability() now accepts a kind parameter ("emp", "mr", "mf", "all").
  kind="all" overlays the empirical and optimized 1-D series on the same axes
  (solid line for emp, dashed line for mr / mf).

Changed

• Internal canonical kind name changed from "empirical" to "emp" for consistency with all other
  short-form kind names (mono, mr, mf, mrc, mfc, mcc).
  The string "empirical" continues to work as an alias.
• plot_marginal_probability(): replaced xlabel parameter with recency_label / frequency_label
  to match the naming convention of plot_probability_surface().
• img/surface_empirical_probability.png renamed to img/surface_emp_probability.png.
• export_probability_csv(kind='all') now outputs all nine models:
  emp, er, ef, mono, mr, mf, mrc, mfc, mcc.