Add 7 example docs covering full API surface (~130 functions)

[sipemu]

Summary

• 7 new example pages with runnable code, expected outputs, and plots covering ~100 previously undocumented functions:
  • Regularized & Specialized Models (lasso, WLS, RLS, BLS, NNLS, isotonic, ridge, elastic net)
  • Generalized Linear Models (Poisson, negative binomial, Tweedie, probit, cloglog)
  • Special Models (ALM robust regression, AID demand classification, dynamic regression)
  • Equivalence Testing — complete TOST guide (all 8 variants)
  • Categorical Data Analysis (binomial, chi-square, G-test, McNemar, Cohen's kappa, phi, contingency)
  • Forecast Model Comparison (Diebold-Mariano, Clark-West, SPA, MCS, energy distance, MMD)
  • Advanced Correlation & Reliability (distance correlation, semi-partial/partial, D'Agostino)
• 3 existing pages edited: added D'Agostino section to hypothesis-testing, cross-references to regression-workflow and ab-testing
• 17 new plots added to gen_plots.py (34 total PNGs), no scipy/sklearn dependencies
• mkdocs.yml nav updated with all new pages
• mkdocs build verified clean

Test plan

• uv run python docs/assets/gen_plots.py generates all 34 PNGs without error
• uv run --with mkdocs-material mkdocs build succeeds
• Spot-check code examples in each new page against actual polars_statistics output
• Verify cross-reference links between pages resolve correctly

🤖 Generated with Claude Code

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.

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