Invert min-max [0,2] scaling to recover the original U matrix.
Source:R/file_utils.R
invert_minmax_scaling.RdStochastic genotype data is stored after min-max scaling: U_scaled = 2 * (U - u_min) / (u_max - u_min). This function exactly inverts that transform using the stored per-variant u_min and u_max values from a companion sidecar file (.afreq or .stochastic_meta.tsv).