feat(algorithms): add KnEA (Knee point-driven EA)

Zhang, Tian & Jin 2015 KnEA: many-objective MOEA that biases survival
selection toward 'knee points' on the Pareto front — points where a
small improvement in one objective costs a large degradation in
another.

Each generation:
- NSGA-II-like loop with offspring + non_dominated_sort
- For the splitting front, identify knee points by perpendicular
  distance from the hyperplane connecting the front's extreme points.
  Members further from the hyperplane (= more 'kneeness') are preferred.
- Survival keeps every knee-tagged member; if room remains, fill from
  remaining members by largest perpendicular distance.

Knee points are intuitively the most attractive points on a Pareto
front when no preference information is available. KnEA pushes the
search toward them at the cost of less uniform front coverage.

src/prelude.rs

@@ -25,7 +25,7 @@ pub use crate::algorithms::{
     AgeMoea, AgeMoeaConfig, AntColonyTsp, AntColonyTspConfig, CmaEs, CmaEsConfig, DifferentialEvolution,
     DifferentialEvolutionConfig, EpsilonMoea, EpsilonMoeaConfig,
     GeneticAlgorithm, GeneticAlgorithmConfig, Grea, GreaConfig, HillClimber, HillClimberConfig, Hype,
-    HypeConfig, Ibea, IbeaConfig, Moead, MoeadConfig, Mopso, MopsoConfig, Nsga2,
+    HypeConfig, Ibea, IbeaConfig, Knea, KneaConfig, Moead, MoeadConfig, Mopso, MopsoConfig, Nsga2,
     Nsga2Config, Nsga3, Nsga3Config, Paes, PaesConfig, ParticleSwarm, PesaII, PesaIIConfig,
     ParticleSwarmConfig, RandomSearch, RandomSearchConfig, Rvea, RveaConfig,
     SimulatedAnnealing,