feat(moeo): add finalize() lifecycle hook for algorithm post-processing

Add virtual finalize() and hasFinalize() to moeoAlgo/moeoPopAlgo hierarchy.
NSGA-II implements finalize() to recompute fitness and diversity assignments
after population modifications (e.g. immigrant integration in island model).

moeo/src/algo/moeoAlgo.h

@@ -42,6 +42,12 @@
  * Abstract class for multi-objective algorithms.
  */
 class moeoAlgo
-  {};
+{
+public:
+    virtual ~moeoAlgo() = default;
+
+    /** Whether this algorithm supports finalize() for post-integration updates. */
+    virtual bool hasFinalize() const { return false; }
+};
 
 #endif /*MOEOALGO_H_*/

moeo/src/algo/moeoNSGAII.h

@@ -148,6 +148,17 @@ public:
         while (continuator (_pop));
     }
 
+    /**
+     * Recompute fitness and diversity assignments on the population.
+     * Useful after integrating immigrants from an island model.
+     * @param _pop the population to finalize
+     */
+    void finalize(eoPop<MOEOT>& _pop) override {
+        fitnessAssignment(_pop);
+        diversityAssignment(_pop);
+    }
+
+    bool hasFinalize() const override { return true; }
 
 protected:
 

moeo/src/algo/moeoPopAlgo.h

@@ -47,6 +47,14 @@
  */
 template < class MOEOT >
 class moeoPopAlgo : public moeoAlgo, public eoAlgo < MOEOT >
-  {};
+{
+public:
+    /**
+     * Recompute fitness/diversity after external population changes (e.g. immigrant integration).
+     * Default implementation is a no-op. Override in subclasses that need it.
+     * @param _pop the population to finalize
+     */
+    virtual void finalize(eoPop<MOEOT>&) {}
+};
 
 #endif /*MOEOPOPALGO_H_*/