Refactored the monolithic compare_curves() workflow into a modular functional analysis API.
compare_curves() is now a soft-deprecated wrapper around the new modular functions.
New functions
functional_curves(): Fits genotype-specific epidemic trajectories using GAM, with support for genotype-level covariates.
functional_distances(): Computes pairwise functional distances among fitted curves and performs hierarchical clustering and permutation testing.
functional_resistance(): Calculates Functional Resistance Index (FRI) and Stability-Adjusted Functional Resistance Index (SAFRI) with support for stratified rankings and bootstrap-supported classification.
suggest_k(): Helper function to recommend GAM smoothing parameters (k_smooth, k_trt, k_env, gamma) based on data structure; supports tidy-eval column names and can infer replication from a data frame.
Enhancements
Added support for genotype-level auxiliary covariates (e.g., heading_group) to adjust functional curves and resistance rankings, allowing for better distinction between genetic resistance and phenological escape.
Improved bootstrap methodology for resistance classification with support for stratified group comparisons.
Added functional_instability() for computing normalized functional instability (NFI) of genotype-by-environment epidemic curves, with optional decomposition into spatial and temporal components.
