Refactor: consistent naming across functions, targets, and pkgdown
Functions: prepare_eda_recipe -> build_eda_recipe,
create_efficiency_plot -> plot_efficiency,
format_class_imbalance_tourney_gt -> format_tournament_gt
Targets: model_inputs_prefix -> baf_model_input_prefix,
tbl_fraud_by_month_data -> fraud_by_month_summary,
model_diag -> diag_fit, winning_params -> best_params,
production_recipe_blueprint -> prod_recipe,
final_eval_data -> test_predictions
pkgdown: restructured reference index into 6 logical sections,
removed stale names and development comments.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>