refactor(swap): 提取 SwapPositionQueries.ActiveByTrade 收口有效持仓查询

- 新增 SwapPositionQueries.ActiveByTrade 静态扩展，收口 'SwapTradeId==X && !Invalid' 规则到单一真相
- 替换 SwapDealService/SwapEodPositionService/SwapTradeService 共 7 处纯重复谓词
- 仅返回 IQueryable，不调 SaveChanges，不动 FindTrade seam / 事务边界；行为保持等价

YLErpDAL/Modules/SwapModule/SwapDealService.cs

@@ -210,7 +210,7 @@ namespace YLErp.Modules.SwapModule
         public UnwindData InitUnwind(int tradeId)
         {
             var td = DbContext.trade.Find(tradeId);
-            var positions = DbContext.swap_position.Where(x => x.SwapTradeId == tradeId && !x.Invalid);
+            var positions = DbContext.swap_position.ActiveByTrade(tradeId);
             var um = DataCacheProvider.GetUnderlyingDataSource().GetData(td.UnderlyingCode);
             bool commodity = ConsGlobal.InstrumentType.CalcTypeIsFutures(um.UnderlyingInstrumentType);
             List<int> eventTyps = new List<int>() { (int)SwapEventTypeEnum.自动互换, (int)SwapEventTypeEnum.互换 };
@@ -355,7 +355,7 @@ namespace YLErp.Modules.SwapModule
         {
             var checkEventTypes = new List<int>() { (int)SwapEventTypeEnum.互换, (int)SwapEventTypeEnum.自动互换 };
             var td = DbContext.trade.Find(tradeId);
-            var positions = DbContext.swap_position.Where(x => x.SwapTradeId == tradeId && !x.Invalid);
+            var positions = DbContext.swap_position.ActiveByTrade(tradeId);
             var um = DataCacheProvider.GetUnderlyingDataSource().GetData(td.UnderlyingCode);
             List<int> eventTypes = new List<int>() { (int)SwapFlowEventTypeEnum.互换, (int)SwapFlowEventTypeEnum.自动互换 };
             var maxIncomeValueDate = GetMaxIncomeValueDate(td);
@@ -460,7 +460,7 @@ namespace YLErp.Modules.SwapModule
             {
                 throw new ServiceException("未找到交易信息");
             }
-            var allpositions = DbContext.swap_position.Where(x => x.SwapTradeId == tradeId && !x.Invalid).ToList();
+            var allpositions = DbContext.swap_position.ActiveByTrade(tradeId).ToList();
             var origPositions = allpositions.Where(x => x.IsInitial).ToList();
             var realPostitions = allpositions.Where(x => !x.IsInitial).ToList();
             // 根因修复(多次部分平仓预付金返还错误)：见 ResolveInterestLegPositions 注释。
@@ -1571,7 +1571,7 @@ namespace YLErp.Modules.SwapModule
         {
             unwindPriceFee = decimal.Parse(unwindPriceFee.ToString("F10"));
             var td = DbContext.trade.Find(tradeid);
-            var positions = DbContext.swap_position.Where(x => x.SwapTradeId == td.id && !x.Invalid);
+            var positions = DbContext.swap_position.ActiveByTrade(td.id);
             List<int> eventTypes = new List<int>() { (int)SwapEventTypeEnum.平仓, (int)SwapEventTypeEnum.互换 };
             var dealDate = valueDate;
             var tradeExtend = DbContext.trade_extend.FirstOrDefault(x => x.TradeId == td.id);

YLErpDAL/Modules/SwapModule/SwapEodPositionService.cs

@@ -133,7 +133,7 @@ namespace YLErp.Modules.SwapModule
         /// <summary>查找交易持仓（生产: DbContext.swap_position.Where；测试: 内存列表）</summary>
         protected virtual List<swap_position> FindSwapPositions(int swapTradeId)
         {
-            return DbContext.swap_position.Where(x => x.SwapTradeId == swapTradeId && !x.Invalid).ToList();
+            return DbContext.swap_position.ActiveByTrade(swapTradeId).ToList();
         }
 
         /// <summary>查找框架合约日终汇总（生产: DbContext.eod_swap.FirstOrDefault；测试: 内存字典）</summary>

YLErpDAL/Modules/SwapModule/SwapPositionQueries.cs

@@ -0,0 +1,18 @@
+using System.Linq;
+using YLErp.DBModels;
+
+namespace YLErp.Modules.SwapModule
+{
+    /// <summary>
+    /// swap_position 查询收口（Query Object）。
+    /// 规则"有效持仓 = SwapTradeId 匹配且未作废(!Invalid)"集中于此，
+    /// 避免多处复制同一谓词导致语义漂移（漏写 !Invalid 即静默出 bug）。
+    /// 仅返回 IQueryable，不调用 SaveChanges，不破坏跟踪/Include/事务边界。
+    /// </summary>
+    public static class SwapPositionQueries
+    {
+        public static IQueryable<swap_position> ActiveByTrade(
+            this IQueryable<swap_position> query, int tradeId)
+            => query.Where(x => x.SwapTradeId == tradeId && !x.Invalid);
+    }
+}

YLErpDAL/Modules/SwapModule/SwapTradeService.cs

@@ -1188,7 +1188,7 @@ namespace YLErp.Modules.SwapModule
                 tradeObj.trade_Initial_Margin = new trade_initial_margin();
             }
             tradeObj.trade_extend = DbContext.trade_extend.FirstOrDefault(x => x.TradeId == intid);
-            tradeObj.swap_positions = DbContext.swap_position.Where(x => x.SwapTradeId == intid && !x.Invalid).ToList();
+            tradeObj.swap_positions = DbContext.swap_position.ActiveByTrade(intid).ToList();
             tradeObj.swap_positions = tradeObj.swap_positions.Where(x => x.PosiQuantity > 0 || x.InterestDirection > 0).ToList();
             var intervalPositions = tradeObj.swap_positions.Where(x => string.IsNullOrEmpty(x.UnderlyingCode) && x.IsInitial).ToList();
             var intervalPositionIds = intervalPositions.Select(s => s.id).ToList();
@@ -1517,7 +1517,7 @@ namespace YLErp.Modules.SwapModule
                 throw new ServiceException("交易不存在");
             }
             bool backToBegin = td.TradeDate == valueDate;
-            var swapPositions = DbContext.swap_position.Where(x => x.SwapTradeId == tradeId && !x.Invalid).ToList();
+            var swapPositions = DbContext.swap_position.ActiveByTrade(tradeId).ToList();
             td.trade_extend = DbContext.trade_extend.FirstOrDefault(x => x.TradeId == td.id);
            
             //展期