feat(operators): expand permutation toolkit

Adds eight operators for permutation (Vec<usize>) decisions:

Initializers
- ShuffledPermutation { n } — random shuffles of [0..n)
- ShuffledMultisetPermutation { repeats_per_id } — random shuffles
  of an arbitrary multiset (e.g., JSS operation strings)

Crossovers (strict permutations only)
- OrderCrossover (OX)
- PartiallyMappedCrossover (PMX)
- CycleCrossover (CX)
- EdgeRecombinationCrossover (ERX)

Mutations (preserve both strict permutations and multisets)
- InversionMutation
- InsertionMutation
- ScrambleMutation

All are re-exported from the prelude. Comprehensive unit tests + doctests
included; the pre-existing SwapMutation is untouched.

src/prelude.rs

@@ -19,9 +19,11 @@ pub use crate::pareto::{
 };
 
 pub use crate::operators::{
-    BitFlipMutation, BoundedGaussianMutation, ClampToBounds, CompositeVariation, GaussianMutation,
-    LevyMutation, PolynomialMutation, ProjectToSimplex, RealBounds, SimulatedBinaryCrossover,
-    SwapMutation,
+    BitFlipMutation, BoundedGaussianMutation, ClampToBounds, CompositeVariation, CycleCrossover,
+    EdgeRecombinationCrossover, GaussianMutation, InsertionMutation, InversionMutation,
+    LevyMutation, OrderCrossover, PartiallyMappedCrossover, PolynomialMutation, ProjectToSimplex,
+    RealBounds, ScrambleMutation, ShuffledMultisetPermutation, ShuffledPermutation,
+    SimulatedBinaryCrossover, SwapMutation,
 };
 
 pub use crate::algorithms::{