feat(algorithms): add PesaII (Pareto Envelope-based Selection Algorithm II)

Corne, Jerram, Knowles & Oates 2001: divides objective space into a
hyperbox grid and uses per-box population counts to drive selection
toward sparsely-populated regions.

Each generation:
- Maintain an external archive of non-dominated members
- Build a hyperbox grid (`grid_divisions` per axis on the archive's
  current axis ranges); count members per box
- Selection picks two parents by region-based tournament: choose two
  random non-empty boxes and take a uniform-random member from the
  one with fewer occupants
- Variation produces an offspring; insert into archive, dropping
  dominated members and (if archive overflows) the most-crowded
  occupant of the most-occupied box

Tests cover non-empty front on Schaffer N.1, deterministic reruns,
and panic on `archive_size == 0`.

src/prelude.rs

@@ -25,7 +25,8 @@ pub use crate::algorithms::{
     AntColonyTsp, AntColonyTspConfig, CmaEs, CmaEsConfig, DifferentialEvolution,
     DifferentialEvolutionConfig,
     GeneticAlgorithm, GeneticAlgorithmConfig, HillClimber, HillClimberConfig, Hype,
-    HypeConfig, Ibea, IbeaConfig, Moead, MoeadConfig, Mopso, MopsoConfig, Nsga2, Nsga2Config, Nsga3, Nsga3Config, Paes, PaesConfig, ParticleSwarm,
+    HypeConfig, Ibea, IbeaConfig, Moead, MoeadConfig, Mopso, MopsoConfig, Nsga2,
+    Nsga2Config, Nsga3, Nsga3Config, Paes, PaesConfig, ParticleSwarm, PesaII, PesaIIConfig,
     ParticleSwarmConfig, RandomSearch, RandomSearchConfig, Rvea, RveaConfig,
     SimulatedAnnealing,
     SimulatedAnnealingConfig, SmsEmoa, SmsEmoaConfig, Spea2, Spea2Config, TabuSearch,