feat: 添加音乐键位字段，更新相关数据结构和接口

backend/app/services/content.go

@@ -160,6 +160,7 @@ func (s *content) Get(ctx context.Context, userID int64, id string) (*content_dt
 		Description: item.Description,
 		Body:        item.Body,
 		MediaUrls:   s.toMediaURLs(accessibleAssets),
+		Meta:        content_dto.Meta{Key: item.Key},
 		IsLiked:     isLiked,
 		IsFavorited: isFavorited,
 	}

backend/app/services/creator.go

@@ -98,7 +98,7 @@ func (s *creator) ListContents(
 	ctx context.Context,
 	userID int64,
 	filter *creator_dto.CreatorContentListFilter,
-) ([]creator_dto.ContentItem, error) {
+) ([]creator_dto.CreatorContentItem, error) {
 	tid, err := s.getTenantID(ctx, userID)
 	if err != nil {
 		return nil, err
@@ -122,12 +122,13 @@ func (s *creator) ListContents(
 		return nil, errorx.ErrDatabaseError.WithCause(err)
 	}
 
-	var data []creator_dto.ContentItem
+	var data []creator_dto.CreatorContentItem
 	for _, item := range list {
-		data = append(data, creator_dto.ContentItem{
+		data = append(data, creator_dto.CreatorContentItem{
 			ID:          cast.ToString(item.ID),
 			Title:       item.Title,
 			Genre:       item.Genre,
+			Key:         item.Key,
 			Views:       int(item.Views),
 			Likes:       int(item.Likes),
 			IsPurchased: false,
@@ -150,6 +151,7 @@ func (s *creator) CreateContent(ctx context.Context, userID int64, form *creator
 			UserID:   uid,
 			Title:    form.Title,
 			Genre:    form.Genre,
+			Key:      form.Key,
 			Status:   consts.ContentStatusPublished,
 		}
 		if err := tx.Content.WithContext(ctx).Create(content); err != nil {
@@ -214,6 +216,7 @@ func (s *creator) UpdateContent(
 		_, err = tx.Content.WithContext(ctx).Where(tx.Content.ID.Eq(cid)).Updates(&models.Content{
 			Title: form.Title,
 			Genre: form.Genre,
+			Key:   form.Key,
 		})
 		if err != nil {
 			return err
@@ -318,6 +321,7 @@ func (s *creator) GetContent(ctx context.Context, userID int64, id string) (*cre
 		ID:             cast.ToString(c.ID),
 		Title:          c.Title,
 		Genre:          c.Genre,
+		Key:            c.Key,
 		Description:    c.Description,
 		Status:         string(c.Status),
 		Price:          price,