Fix zombie renderer instances on same-map SMSG_NEW_WORLD teleports

When SMSG_NEW_WORLD fires with the same map ID (dungeon wing teleporters,
GM teleports, etc.), entityManager.clear() was called but renderer
instances in creatureInstances_/playerInstances_/gameObjectInstances_
were never despawned.  Fresh CREATE_OBJECTs from the server hit the
early-return guard (guid already in creatureInstances_) and were skipped,
leaving entities in the entity manager without matching renderer state.

Fix: pass isSameMap as isInitialEntry to the world-entry callback.  This
routes same-map SMSG_NEW_WORLD through the reconnect path which properly
despawns all renderer instances before the server resends CREATE_OBJECTs.

src/game/game_handler.cpp

@@ -17111,9 +17111,13 @@ void GameHandler::handleNewWorld(network::Packet& packet) {
         LOG_INFO("Sent MSG_MOVE_WORLDPORT_ACK");
     }
 
-    // Reload terrain at new position
+    // Reload terrain at new position.
+    // Pass isSameMap as isInitialEntry so the application despawns and
+    // re-registers renderer instances before the server resends CREATE_OBJECTs.
+    // Without this, same-map SMSG_NEW_WORLD (dungeon wing teleporters, etc.)
+    // leaves zombie renderer instances that block fresh entity spawns.
     if (worldEntryCallback_) {
-        worldEntryCallback_(mapId, serverX, serverY, serverZ, false);
+        worldEntryCallback_(mapId, serverX, serverY, serverZ, isSameMap);
     }
 }