refactor(phase1): Update trading module exports

backend/app/trading/__init__.py

@@ -8,10 +8,19 @@ Trading Engine Module
 - 장 스케줄 관리
 """
 
+from app.trading.kis_client import KISClient, kis_client, real_market_client
+from app.trading.order_manager import OrderManager, order_manager
+from app.trading.market_data import MarketDataProvider, market_data_provider
+
 __all__ = [
+    # Classes
     "KISClient",
-    "WSClient",
     "OrderManager",
-    "WSManager",
+    "MarketDataProvider",
-    "TradingScheduler",
+    
+    # Singleton instances
+    "kis_client",
+    "real_market_client",
+    "order_manager",
+    "market_data_provider",
 ]