indicate balancing winner better

src/balancing/ArenaSimulation.h

@@ -37,6 +37,7 @@ struct ArenaStatus
 
     TeamStatus teams[2];
     bool finished = false;
+    int winnerTeam = -1;  // 0 or 1 when finished; -1 while running
 };
 
 class ArenaSimulation
@@ -77,6 +78,7 @@ private:
     EntityId m_team2HqId;
 
     bool m_finished;
+    int m_winnerTeam;
     std::atomic<bool> m_stopRequested;
 
     mutable std::mutex m_statusMutex;