refactor(accrual): 拆分FundingLegAccrual→SimpleInterestAccrual/CompoundInterestAccrual

单利与复利语义完全不同(单利本金恒定/复利重置日并本金),
拆成两个独立静态类,各自只含自己的方法:

SimpleInterestAccrual:
- AccrueEod (原AccrueSimpleEod)
- AccruePeriod (原AccrueSimplePeriod)

CompoundInterestAccrual:
- EodBasis (原CompoundEodBasis)
- AccrueEod (原AccrueCompoundEod)
- AccruePeriod (原AccrueCompoundPeriod)

方法名去掉Simple/Compound前缀(类名已携带类型),消除冗余
SwapModule零回归(7基线/510通过)

UnitTestProject/Modules/SwapModule/Accrual/CompoundPeriodShadowTest.cs

@@ -7,7 +7,7 @@ using YLErp.Modules.SwapModule.Accrual;
 namespace UnitTestProject.Modules.SwapModule.Accrual
 {
     /// <summary>
-    /// 影子测试：CalcDailyCompoundInterest（旧逐日循环）vs FundingLegAccrual.AccrueCompoundPeriod（新分段纯函数）。
+    /// 影子测试：CalcDailyCompoundInterest（旧逐日循环）vs CompoundInterestAccrual.AccruePeriod（新分段纯函数）。
     /// </summary>
     [TestClass]
     public class CompoundPeriodShadowTest
@@ -86,7 +86,7 @@ namespace UnitTestProject.Modules.SwapModule.Accrual
                 (StartDate.AddDays(7), allInRate),
                 (StartDate.AddDays(14), allInRate),
             };
-            var result = FundingLegAccrual.AccrueCompoundPeriod(
+            var result = CompoundInterestAccrual.AccruePeriod(
                 notional: Notional,
                 segmentRates: segRates,
                 startDate: StartDate,
@@ -133,7 +133,7 @@ namespace UnitTestProject.Modules.SwapModule.Accrual
                 (StartDate.AddDays(7), allInRate),
                 (StartDate.AddDays(14), allInRate),
             };
-            var result = FundingLegAccrual.AccrueCompoundPeriod(
+            var result = CompoundInterestAccrual.AccruePeriod(
                 notional: Notional * closePct,
                 segmentRates: segRates,
                 startDate: StartDate,
@@ -177,7 +177,7 @@ namespace UnitTestProject.Modules.SwapModule.Accrual
                 (StartDate.AddDays(7), allInRate),
                 (StartDate.AddDays(14), allInRate),
             };
-            var result = FundingLegAccrual.AccrueCompoundPeriod(
+            var result = CompoundInterestAccrual.AccruePeriod(
                 notional: Notional,
                 segmentRates: segRates,
                 startDate: StartDate,