fix mutually canceling orbits

src/lib/ecs/component/MovementIntentComponent.h

@@ -11,4 +11,7 @@ struct MovementIntentComponent
     bool      active = false;
     QVector2D target;                   // straight-line destination, or orbit center when orbitRadius_tiles > 0
     float     orbitRadius_tiles = 0.0f; // 0 ⇒ go straight to target; >0 ⇒ orbit target at this radius
+    QVector2D orbitCenterVelocity_tpt;  // velocity of the orbit center (0 for a static center); the orbit
+                                        // sense is resolved relative to this so a moving target's own motion
+                                        // does not bias it
 };