refactor(dividend): 优化除权除息计算逻辑并改进数据类型精度

- 将除权除息相关数值字段从 double 类型改为 decimal 类型以提高精度
- 重构了红利比率计算方法 GetRatio，新增 GetRatioDecimal 方法使用 decimal 计算
- 修改价格和持仓数量计算逻辑，统一使用 decimal 进行高精度运算
- 更新数据库查询逻辑，将篮子标的判断从 IsBasket() 方法改为 CommodityCode 条件
- 优化 AddDividendInfos 方法中的批量处理逻辑，增加业务键冲突检测
- 添加数据源标识字段 DataSource 和来源更新时间字段 SourceUpdatedAt
- 新增 FindExDividendByBusinessKey 和 MergeNonZeroDividendValues 辅助方法
- 更新结算服务中除权除息信息的获取方式，使用字典查找替代 LINQ JOIN
- 修复前端保存除权信息时的响应处理逻辑
- 为基金类型也开放除权功能，不仅限于股票类型
- 添加单元测试验证篮子标的查询翻译逻辑的正确性

UnitTestProject/Modules/EodModule/EodSettlementTaskTest.cs

@@ -123,7 +123,7 @@ namespace YLErp.Modules.EodModule
             {
                 UnderlyingCode = "002043.SZ",
                 ExDividendDate = new DateTime(2020, 7, 6),
-                GiveCashAmount = 2.5,
+                GiveCashAmount = 2.5m,
                 GiveShareAmount = 0,
                 RationedSharesAmount = 0,
                 RationedSharesPrice = 0,
@@ -135,7 +135,7 @@ namespace YLErp.Modules.EodModule
             {
                 UnderlyingCode = "600406.SH",
                 ExDividendDate = new DateTime(2020, 7, 8),
-                GiveCashAmount = 2.9,
+                GiveCashAmount = 2.9m,
                 GiveShareAmount = 0,
                 RationedSharesAmount = 0,
                 RationedSharesPrice = 0,
@@ -147,7 +147,7 @@ namespace YLErp.Modules.EodModule
             {
                 UnderlyingCode = "600406.SH",
                 ExDividendDate = new DateTime(2020, 7, 8),
-                GiveCashAmount = 2.9,
+                GiveCashAmount = 2.9m,
                 GiveShareAmount = 0,
                 RationedSharesAmount = 0,
                 RationedSharesPrice = 0,
@@ -159,7 +159,7 @@ namespace YLErp.Modules.EodModule
             {
                 UnderlyingCode = "601021.SH",
                 ExDividendDate = new DateTime(2020, 7, 8),
-                GiveCashAmount = 2.0006,
+                GiveCashAmount = 2.0006m,
                 GiveShareAmount = 0,
                 RationedSharesAmount = 0,
                 RationedSharesPrice = 0,
@@ -171,7 +171,7 @@ namespace YLErp.Modules.EodModule
             {
                 UnderlyingCode = "300001.SZ",
                 ExDividendDate = new DateTime(2020, 7, 13),
-                GiveCashAmount = 0.2,
+                GiveCashAmount = 0.2m,
                 GiveShareAmount = 0,
                 RationedSharesAmount = 0,
                 RationedSharesPrice = 0,