fix: 修复 scheduler.py 和 sim_trade.py 中智能引擎调用连接泄漏

- scheduler.py: job_morning_trade/job_afternoon_trade 智能引擎 put_db 移到 finally
- sim_trade.py: trigger_trade 降级路径 put_db 移到 finally，初始化 conn=None
- 统一使用 smart_conn 变量名避免与外层 conn 冲突

stock-html/routes/sim_trade.py

@@ -648,15 +648,22 @@ def trigger_trade():
         # 降级: 使用旧引擎
         from services.scheduler import execute_auto_trade_for_user
         
-        conn = get_db()
-        if conn:
-            cur = conn.cursor(cursor_factory=RealDictCursor)
-            cur.execute("SELECT trade_quantity FROM sim_config WHERE user_id = %s", (user_id,))
-            config = cur.fetchone()
-            trade_quantity = config['trade_quantity'] if config else 1000
-            put_db(conn)
-        else:
+        conn = None
+        try:
+            conn = get_db()
+            if conn:
+                cur = conn.cursor(cursor_factory=RealDictCursor)
+                cur.execute("SELECT trade_quantity FROM sim_config WHERE user_id = %s", (user_id,))
+                config = cur.fetchone()
+                trade_quantity = config['trade_quantity'] if config else 1000
+            else:
+                trade_quantity = 1000
+        except Exception as e:
+            print(f"[trigger_trade] 获取交易配置失败: {e}")
             trade_quantity = 1000
+        finally:
+            if conn:
+                put_db(conn)
         
         result = execute_auto_trade_for_user(user_id, trade_quantity)