Gaussian mutation. Adds zero-mean Gaussian noise to each gene independently with probability mutation_per_gene_rate (default 1.0). Each perturbation is scaled by gaussian_sigma (default 0.1) times the gene's bound range. Output is clamped to bounds.

Uniform mutation. Replaces each gene with uniform random in [lo, hi] with probability mutation_per_gene_rate (default 1 / length).