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/CompoundEodShadowTest.cs

@@ -13,7 +13,7 @@ using YLErp.Core.Interest;
 namespace UnitTestProject.Modules.SwapModule.Accrual
 {
     /// <summary>
-    /// 影子测试：CalcDailyCompoundInterestByEod（旧逐日循环）vs FundingLegAccrual.AccrueCompoundEod（新纯函数）。
+    /// 影子测试：CalcDailyCompoundInterestByEod（旧逐日循环）vs CompoundInterestAccrual.AccrueEod（新纯函数）。
     /// 构造同一组参数，两套实现并行跑，断言结果一致（到分）。
     /// </summary>
     [TestClass]
@@ -99,7 +99,7 @@ namespace UnitTestProject.Modules.SwapModule.Accrual
             var rate = FundingLegRate.Fixed(FixedRate);
             var policy = new AccrualPolicy(AccrualBoundary.Both, true, 7, AnnualDays, true);
             var remainingPercent = Math.Max(0m, Math.Min(1m, Notional / Notional));
-            var result = FundingLegAccrual.AccrueCompoundEod(
+            var result = CompoundInterestAccrual.AccrueEod(
                 50_000m, Notional, Notional, 1m, rate, policy,
                 isResetDay: true, remainingPercent, EodDate);
 
@@ -131,7 +131,7 @@ namespace UnitTestProject.Modules.SwapModule.Accrual
             // 新方法
             var rate = FundingLegRate.Fixed(FixedRate);
             var policy = new AccrualPolicy(AccrualBoundary.Both, true, 7, AnnualDays, true);
-            var result = FundingLegAccrual.AccrueCompoundEod(
+            var result = CompoundInterestAccrual.AccrueEod(
                 30_000m, Notional, Notional, 1m, rate, policy,
                 isResetDay: false, 0m, nonResetDate);