wifi盟主奖励和运营中心奖励取值逻辑修改，取最新的交易

AppStart/Helper/LeaderPrizeService.cs

@@ -59,7 +59,7 @@ namespace MySystem
                                     int tradeCount = db.WifiTradeRecord.Count(m => m.SnNo == pos.PosSn);
                                     if (tradeCount > 0)
                                     {
-                                        ChangeAmount = db.WifiTradeRecord.Where(m => m.SnNo == pos.PosSn).OrderByDescending(m => m.Id).TradeAmount * 0.015M;
+                                        ChangeAmount = db.WifiTradeRecord.Where(m => m.SnNo == pos.PosSn).OrderByDescending(m => m.Id).FirstOrDefault().TradeAmount * 0.015M;
                                         ChangeAmount = PublicFunction.NumberFormat(ChangeAmount);
                                     }
                                     else

AppStart/Helper/OperatePrizeService.cs

@@ -78,7 +78,7 @@ namespace MySystem
                                         int tradeCount = db.WifiTradeRecord.Count(m => m.SnNo == pos.PosSn);
                                         if (tradeCount > 0)
                                         {
-                                            ChangeAmount = db.WifiTradeRecord.Where(m => m.SnNo == pos.PosSn).OrderByDescending(m => m.Id).TradeAmount * 0.005M;
+                                            ChangeAmount = db.WifiTradeRecord.Where(m => m.SnNo == pos.PosSn).OrderByDescending(m => m.Id).FirstOrDefault().TradeAmount * 0.005M;
                                             ChangeAmount = PublicFunction.NumberFormat(ChangeAmount);
                                         }
                                         else