feat(algorithms): add CMA-ES (Covariance Matrix Adaptation Evolution Strategy)

Hansen & Ostermeier 2001 CMA-ES, the canonical real-valued
single-objective stochastic optimizer. Implements the full (μ/μ_w, λ)
update with rank-μ + rank-1 covariance updates and cumulative step-size
adaptation:

- Sample λ offspring from N(mean, σ² · C)
- Select the μ best, weight them, recompute mean
- Update evolution paths p_σ (step size) and p_c (covariance)
- Rank-1 update of C from p_c, plus rank-μ update from selected offspring
- Adapt σ via |p_σ| / E‖N(0,I)‖

Eigendecomposition (used to convert C into its B·D form for sampling
N(0, σ²·C)) goes through the new internal Jacobi helper, recomputed
every `eigen_decomposition_period` generations to amortize cost.

Vec<f64> decisions only. Bounds taken from a `RealBounds` field; mean
and offspring are clamped per dimension. Single-objective only.

Hyperparameters use the standard CMA-ES defaults (μ=λ/2, weights from
Hansen's tutorial, c_σ, c_c, c_1, c_μ, d_σ all formulae from §7.1).

Tests cover: convergence on Sphere1D and 5-D Rosenbrock, deterministic
reruns, panic on multi-objective, panic on `population_size < 4`.

src/prelude.rs

@@ -22,9 +22,9 @@ pub use crate::operators::{
 };
 
 pub use crate::algorithms::{
-    DifferentialEvolution, DifferentialEvolutionConfig, GeneticAlgorithm,
-    GeneticAlgorithmConfig, HillClimber, HillClimberConfig, Moead, MoeadConfig, Nsga2,
-    Nsga2Config, Nsga3, Nsga3Config, Paes, PaesConfig, ParticleSwarm, ParticleSwarmConfig,
-    RandomSearch, RandomSearchConfig, SimulatedAnnealing, SimulatedAnnealingConfig, Spea2,
-    Spea2Config, TabuSearch, TabuSearchConfig,
+    CmaEs, CmaEsConfig, DifferentialEvolution, DifferentialEvolutionConfig,
+    GeneticAlgorithm, GeneticAlgorithmConfig, HillClimber, HillClimberConfig, Moead,
+    MoeadConfig, Nsga2, Nsga2Config, Nsga3, Nsga3Config, Paes, PaesConfig, ParticleSwarm,
+    ParticleSwarmConfig, RandomSearch, RandomSearchConfig, SimulatedAnnealing,
+    SimulatedAnnealingConfig, Spea2, Spea2Config, TabuSearch, TabuSearchConfig,
 };