feat(billing): 新增逾期账单自动标记定时任务

1. 新增Hangfire定时任务BillingOverdueProcessJob
2. 修复逾期账单查询条件过宽问题
3. 默认每10分钟执行一次逾期检查

src/Infrastructure/TakeoutSaaS.Infrastructure/App/Persistence/Repositories/TenantBillingRepository.cs

@@ -102,14 +102,13 @@ public sealed class TenantBillingRepository(TakeoutAppDbContext context) : ITena
         // 1. 以当前 UTC 时间作为逾期判断基准
         var now = DateTime.UtcNow;
 
-        // 2. (空行后) 查询逾期且未结清/未取消的账单
+        // 2. (空行后) 查询逾期且仍处于待支付的账单（仅 Pending 才允许自动切换为 Overdue）
         return await context.TenantBillingStatements
             .IgnoreQueryFilters()
             .AsNoTracking()
             .Where(x => x.DeletedAt == null
                         && x.DueDate < now
-                        && x.Status != TenantBillingStatus.Paid
-                        && x.Status != TenantBillingStatus.Cancelled)
+                        && x.Status == TenantBillingStatus.Pending)
             .OrderBy(x => x.DueDate)
             .ToListAsync(cancellationToken);
     }

src/Infrastructure/TakeoutSaaS.Infrastructure/App/Services/BillingDomainService.cs

@@ -147,14 +147,14 @@ public sealed class BillingDomainService(
     /// <inheritdoc />
     public async Task<int> ProcessOverdueBillingsAsync(CancellationToken cancellationToken = default)
     {
-        // 1. 查询当前已逾期且未支付/未取消的账单（由仓储按 DueDate 筛选）
+        // 1. 查询当前已超过到期日且仍处于待支付的账单（由仓储按 DueDate + Status 筛选）
         var overdueBillings = await billingRepository.GetOverdueBillingsAsync(cancellationToken);
         if (overdueBillings.Count == 0)
         {
             return 0;
         }
 
-        // 2. (空行后) 批量标记逾期（仅处理 Pending）
+        // 2. (空行后) 批量标记逾期（防御性：再次判断 Pending）
         var processedAt = DateTime.UtcNow;
         var updated = 0;
         foreach (var billing in overdueBillings)