refactor(swap-test): 抽取 TestableSwapEodPositionService 公共基类收敛重复 Stub

- 新建 TestableSwapEodPositionService 收敛 8/8 Stub 重复的高频 override
  (PersistEodSwapPosition/SaveAllChanges/GetCurrencyRate/AddClientCash)
  + 统一 OptUserInfo 构造 + PersistedPositions/SaveChangesCount 输出捕获
- SwapEodPositionService.DealInterests 改 protected virtual（行为零变化）
- 8 个 ScenarioTest 改为继承基类，删除重复 override
- 消灭 DealInterestsScenarioTest/DealInterestsGoldenReplayTest 的反射调用
  (typeof().GetMethod().Invoke → 直接调用 DealInterests)

验证：dotnet build 0 错误；dotnet test SwapModule 284通过/6跳过/0失败

UnitTestProject/Modules/SwapModule/DealFloatPositionsScenarioTest.cs

@@ -25,7 +25,7 @@ namespace YLErp.Modules.SwapModule
 
         #region Stub
 
-        private sealed class StubEodService : SwapEodPositionService
+        private sealed class StubEodService : TestableSwapEodPositionService
         {
             // 可注入的外部数据
             public decimal UnderlyingPrice { get; set; } = 1.00m;
@@ -34,7 +34,7 @@ namespace YLErp.Modules.SwapModule
             public decimal TaxRate { get; set; } = 0m;
             public string UnderlyingCode { get; set; } = "210210.IB";
 
-            public StubEodService() : base(new OptUserInfo(0, nameof(DealFloatPositionsScenarioTest), OptUserFrom.UnitTest))
+            public StubEodService() : base(nameof(DealFloatPositionsScenarioTest))
             {
             }
 
@@ -55,11 +55,6 @@ namespace YLErp.Modules.SwapModule
                 return BondPayment;
             }
 
-            protected override void SaveAllChanges() { }
-
-            protected override double GetCurrencyRate(string quoteCurrency, string settlementCurrency, DateTime valueDate, bool seekPreday, CurrencyRateType currencyRateType)
-                => 1.0;
-
             // DealFloatPositions 和子方法都是 protected，通过 public 包装暴露
             public List<eod_swap_position> ExecuteDealFloatPositions(
                 List<swap_position> posiList, List<swap_position> realPosiList,