feat: 添加推送通知功能，支持订阅和发送通知

Service/MessageRecordService.cs

@@ -12,7 +12,7 @@ public interface IMessageRecordService
     Task<long> GetUnreadCountAsync();
 }
 
-public class MessageRecordService(IMessageRecordRepository messageRepo) : IMessageRecordService
+public class MessageRecordService(IMessageRecordRepository messageRepo, INotificationService notificationService) : IMessageRecordService
 {
     public async Task<(IEnumerable<MessageRecord> List, long Total)> GetPagedListAsync(int pageIndex, int pageSize)
     {
@@ -37,7 +37,12 @@ public class MessageRecordService(IMessageRecordRepository messageRepo) : IMessa
             Content = content,
             IsRead = false
         };
-        return await messageRepo.AddAsync(message);
+        var result = await messageRepo.AddAsync(message);
+        if (result)
+        {
+            await notificationService.SendNotificationAsync($"新增的账单通知: {title}");
+        }
+        return result;
     }
 
     public async Task<bool> MarkAsReadAsync(long id)