Replace print statements with proper logging for consistent log file output

alpaca_trader/api.py

@@ -95,5 +95,6 @@ class AlpacaClient:
                 return float(status.filled_avg_price)
             return None
         except Exception as e:
-            print(f"Order placement error: {e}")
+            import logging
+            logging.error(f"Order placement error: {e}")
             return None