fix(go): repair migration wire contracts and runtime lifecycle; document incomplete port

internal/gameserver/traffic.go

@@ -30,6 +30,7 @@ type RoadNetworkData struct {
 }
 
 type CityTrafficEngine struct {
+	wg          sync.WaitGroup
 	mu          sync.RWMutex
 	vehicles    map[uint64]*TrafficVehicle
 	lanes       []RoadLane
@@ -97,23 +98,29 @@ func (te *CityTrafficEngine) Start(ctx context.Context) {
 			LaneLength: lane.Length,
 		}
 	}
+	count := len(te.vehicles)
+	te.wg.Add(1)
 	te.mu.Unlock()
 
-	log.Printf("[TRAFFIC] CityTrafficEngine started with %d simulated AI vehicles", len(te.vehicles))
+	log.Printf("[TRAFFIC] CityTrafficEngine started with %d simulated AI vehicles", count)
 	go te.runLoop(ctx)
 }
 
 func (te *CityTrafficEngine) Stop() {
 	te.mu.Lock()
-	defer te.mu.Unlock()
 	if te.cancel != nil {
 		te.cancel()
 	}
 	te.isRunning = false
+	te.mu.Unlock()
+	te.wg.Wait()
+	te.mu.Lock()
 	te.vehicles = make(map[uint64]*TrafficVehicle)
+	te.mu.Unlock()
 }
 
 func (te *CityTrafficEngine) runLoop(ctx context.Context) {
+	defer te.wg.Done()
 	ticker := time.NewTicker(150 * time.Millisecond) // ~6.7 Hz downsampled traffic lane updates
 	defer ticker.Stop()
 
@@ -151,6 +158,9 @@ func (te *CityTrafficEngine) tick(dt float32) {
 	methodID := protocol.MethodGetMethodIDDefault("SyncAetherAIVehicleLaneDatas", 68582850)
 	sessions := te.server.GetActiveSessions()
 	for _, sess := range sessions {
+		if !sess.ready.Load() || sess.hangup.Load() {
+			continue
+		}
 		_ = sess.NotifyData(methodID, payload)
 	}
 }