feat: 实现用户通知系统，包含通知模型、数据操作、业务逻辑及相关API接口。

internal/service/notification_service.go

@@ -0,0 +1,47 @@
+package service
+
+import (
+    "accounting-app/internal/models"
+    "accounting-app/internal/repository"
+)
+
+type NotificationService struct {
+    repo *repository.NotificationRepository
+}
+
+func NewNotificationService(repo *repository.NotificationRepository) *NotificationService {
+    return &NotificationService{repo: repo}
+}
+
+func (s *NotificationService) CreateNotification(userID uint, title, content string, notifType models.NotificationType, link string) error {
+    notification := &models.Notification{
+        UserID:  userID,
+        Title:   title,
+        Content: content,
+        Type:    notifType,
+        Link:    link,
+    }
+    return s.repo.Create(notification)
+}
+
+func (s *NotificationService) GetNotifications(userID uint, page, limit int, isRead *bool) ([]models.Notification, int64, error) {
+    if page < 1 {
+        page = 1
+    }
+    if limit < 1 {
+        limit = 10
+    }
+    return s.repo.FindAll(userID, page, limit, isRead)
+}
+
+func (s *NotificationService) GetUnreadCount(userID uint) (int64, error) {
+    return s.repo.CountUnread(userID)
+}
+
+func (s *NotificationService) MarkAsRead(id uint, userID uint) error {
+    return s.repo.MarkAsRead(id, userID)
+}
+
+func (s *NotificationService) MarkAllAsRead(userID uint) error {
+    return s.repo.MarkAllAsRead(userID)
+}