refactor AI system

src/lib/ecs/component/RetreatBehavior.h

@@ -0,0 +1,13 @@
+#pragma once
+
+#include <QVector2D>
+
+// Player-only retreat behavior (replaces HomeReturnBehaviorComponent). Scored
+// high when HP is low, or when an enemy is in sensor range and the ship cannot
+// fight back. The executor moves the ship to retreatPoint (the rally point).
+struct RetreatBehavior
+{
+    float     retreatHpFraction = 0.0f;
+    QVector2D retreatPoint;
+    float     score = 0.0f;
+};