make repair ships standby with rest of fleet if there is no one to repair (instead of advancing towards the enemy stations)

src/lib/ecs/system/AiSystem.h

@@ -14,6 +14,8 @@
 #include "RetreatExecutor.h"
 #include "SalvageScrapEvaluator.h"
 #include "SalvageScrapExecutor.h"
+#include "StandbyEvaluator.h"
+#include "StandbyExecutor.h"
 
 class BuildingSystem;
 class EntityAdmin;
@@ -38,6 +40,7 @@ private:
     void selectWinningBehaviors(EntityAdmin& admin);
 
     AdvanceEvaluator      m_advanceEvaluator;
+    StandbyEvaluator      m_standbyEvaluator;
     RallyEvaluator        m_rallyEvaluator;
     RetreatEvaluator      m_retreatEvaluator;
     AttackEvaluator       m_attackEvaluator;
@@ -46,6 +49,7 @@ private:
     DeliverScrapEvaluator m_deliverScrapEvaluator;
 
     AdvanceExecutor      m_advanceExecutor;
+    StandbyExecutor      m_standbyExecutor;
     RallyExecutor        m_rallyExecutor;
     RetreatExecutor      m_retreatExecutor;
     AttackExecutor       m_attackExecutor;