feat(finance): add cost management backend module

src/Domain/TakeoutSaaS.Domain/Finance/Entities/FinanceCostEntry.cs

@@ -0,0 +1,35 @@
+using TakeoutSaaS.Domain.Finance.Enums;
+using TakeoutSaaS.Shared.Abstractions.Entities;
+
+namespace TakeoutSaaS.Domain.Finance.Entities;
+
+/// <summary>
+/// 成本录入月度汇总实体（按维度 + 分类）。
+/// </summary>
+public sealed class FinanceCostEntry : MultiTenantEntityBase
+{
+    /// <summary>
+    /// 统计维度。
+    /// </summary>
+    public FinanceCostDimension Dimension { get; set; } = FinanceCostDimension.Tenant;
+
+    /// <summary>
+    /// 门店标识（租户汇总维度为空）。
+    /// </summary>
+    public long? StoreId { get; set; }
+
+    /// <summary>
+    /// 成本月份（统一存储为 UTC 每月第一天 00:00:00）。
+    /// </summary>
+    public DateTime CostMonth { get; set; }
+
+    /// <summary>
+    /// 成本分类。
+    /// </summary>
+    public FinanceCostCategory Category { get; set; }
+
+    /// <summary>
+    /// 分类总金额。
+    /// </summary>
+    public decimal TotalAmount { get; set; }
+}