Add composite fitness calculation

Author: seofernando25

framework/fitness.py

@@ -0,0 +1,22 @@
+def calculate_composite_fitness(metrics: dict[str, float]) -> float:
+    """Calculate composite fitness score from evaluation metrics."""
+    # Extract metrics
+    f1_macro = metrics.get("f1_macro", 0.0)
+    recall_macro = metrics.get("recall_macro", 0.0)
+    roc_auc = metrics.get("roc_auc", 0.0)
+    precision_macro = metrics.get("precision_macro", 0.0)
+    accuracy = metrics.get("accuracy", 0.0)
+    f1_micro = metrics.get("f1_micro", 0.0)
+    
+    # Composite fitness
+    composite_fitness = (
+        0.30 * f1_macro +
+        0.20 * recall_macro +
+        0.20 * roc_auc +
+        0.15 * precision_macro +
+        0.10 * accuracy +
+        0.05 * f1_micro
+    )
+    
+    return composite_fitness
+