feat: 实现订阅自动化定时任务系统

新增定时任务 (Scheduler Module):
- SubscriptionAutoRenewalJob: 自动续费账单生成
- SubscriptionRenewalReminderJob: 续费提醒发送 (7/3/1天)
- SubscriptionExpiryCheckJob: 到期检查与宽限期处理

新增 Command/Handler:
- ProcessAutoRenewalCommand: 处理自动续费逻辑
- ProcessRenewalRemindersCommand: 处理续费提醒逻辑
- ProcessSubscriptionExpiryCommand: 处理订阅到期逻辑

配置项 (SubscriptionAutomationOptions):
- AutoRenewalDaysBeforeExpiry: 到期前N天生成续费账单
- ReminderDaysBeforeExpiry: 提醒天数数组
- GracePeriodDays: 宽限期天数
- 各任务执行小时配置

Repository 增强:
- ISubscriptionRepository: 新增自动化查询方法
- ITenantBillingRepository: 新增账单创建方法
- ITenantNotificationRepository: 新增通知创建方法

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

src/Infrastructure/TakeoutSaaS.Infrastructure/App/Repositories/EfTenantNotificationRepository.cs

@@ -56,6 +56,23 @@ public sealed class EfTenantNotificationRepository(TakeoutAppDbContext context)
             .FirstOrDefaultAsync(x => x.TenantId == tenantId && x.Id == notificationId, cancellationToken);
     }
 
+    /// <inheritdoc />
+    public Task<bool> ExistsByMetadataAsync(
+        long tenantId,
+        string title,
+        string metadataJson,
+        DateTime sentAfter,
+        CancellationToken cancellationToken = default)
+    {
+        return context.TenantNotifications.AsNoTracking()
+            .AnyAsync(
+                x => x.TenantId == tenantId
+                     && x.Title == title
+                     && x.MetadataJson == metadataJson
+                     && x.SentAt >= sentAfter,
+                cancellationToken);
+    }
+
     /// <inheritdoc />
     public Task AddAsync(TenantNotification notification, CancellationToken cancellationToken = default)
     {