make ships orbit their targets

src/lib/ecs/component/RepairBehavior.h

@@ -11,5 +11,6 @@ struct RepairBehavior
 {
     std::optional<entt::entity> currentTarget;
     float                       maxRepairRange_tiles = 0.0f;
+    float                       orbitRadius_tiles = 0.0f;  // REQ-SHP-ORBIT
     float                       score = 0.0f;
 };