docs: add xml comments for tenant modules

src/Domain/TakeoutSaaS.Domain/Tenants/Repositories/ITenantBillingRepository.cs

@@ -11,6 +11,15 @@ namespace TakeoutSaaS.Domain.Tenants.Repositories;
 /// </summary>
 public interface ITenantBillingRepository
 {
+    /// <summary>
+    /// 查询账单列表，按状态与时间范围筛选。
+    /// </summary>
+    /// <param name="tenantId">租户 ID。</param>
+    /// <param name="status">账单状态。</param>
+    /// <param name="from">开始时间（UTC）。</param>
+    /// <param name="to">结束时间（UTC）。</param>
+    /// <param name="cancellationToken">取消标记。</param>
+    /// <returns>账单集合。</returns>
     Task<IReadOnlyList<TenantBillingStatement>> SearchAsync(
         long tenantId,
         TenantBillingStatus? status,
@@ -18,13 +27,41 @@ public interface ITenantBillingRepository
         DateTime? to,
         CancellationToken cancellationToken = default);
 
+    /// <summary>
+    /// 按 ID 获取账单。
+    /// </summary>
+    /// <param name="tenantId">租户 ID。</param>
+    /// <param name="billingId">账单 ID。</param>
+    /// <param name="cancellationToken">取消标记。</param>
+    /// <returns>账单实体或 null。</returns>
     Task<TenantBillingStatement?> FindByIdAsync(long tenantId, long billingId, CancellationToken cancellationToken = default);
 
+    /// <summary>
+    /// 按账单编号获取账单。
+    /// </summary>
+    /// <param name="tenantId">租户 ID。</param>
+    /// <param name="statementNo">账单编号。</param>
+    /// <param name="cancellationToken">取消标记。</param>
+    /// <returns>账单实体或 null。</returns>
     Task<TenantBillingStatement?> FindByStatementNoAsync(long tenantId, string statementNo, CancellationToken cancellationToken = default);
 
+    /// <summary>
+    /// 新增账单。
+    /// </summary>
+    /// <param name="bill">账单实体。</param>
+    /// <param name="cancellationToken">取消标记。</param>
     Task AddAsync(TenantBillingStatement bill, CancellationToken cancellationToken = default);
 
+    /// <summary>
+    /// 更新账单。
+    /// </summary>
+    /// <param name="bill">账单实体。</param>
+    /// <param name="cancellationToken">取消标记。</param>
     Task UpdateAsync(TenantBillingStatement bill, CancellationToken cancellationToken = default);
 
+    /// <summary>
+    /// 保存变更。
+    /// </summary>
+    /// <param name="cancellationToken">取消标记。</param>
     Task SaveChangesAsync(CancellationToken cancellationToken = default);
 }