fix(canvas): 画布 - 防止旧内容覆盖并支持版本历史恢复

backend/internal/canvas/user_data_page.go

@@ -40,6 +40,7 @@ type CanvasLibrarySummary struct {
 	ID           string           `json:"id"`
 	ProjectID    string           `json:"projectId,omitempty"`
 	Title        string           `json:"title"`
+	Revision     int64            `json:"revision"`
 	CreatedAt    time.Time        `json:"createdAt"`
 	UpdatedAt    time.Time        `json:"updatedAt"`
 	NodeCount    int              `json:"nodeCount"`
@@ -107,7 +108,7 @@ func (s *Service) UserCanvasProjectsPage(userID string, page int, pageSize int,
 			item["metadata"] = metadata
 			preview = append(preview, item)
 		}
-		result.Projects = append(result.Projects, CanvasLibrarySummary{ID: project.ID, ProjectID: project.ProjectID, Title: project.Title, CreatedAt: project.CreatedAt, UpdatedAt: project.UpdatedAt, NodeCount: len(document.Nodes), PreviewNodes: preview})
+		result.Projects = append(result.Projects, CanvasLibrarySummary{ID: project.ID, ProjectID: project.ProjectID, Title: project.Title, Revision: project.Revision, CreatedAt: project.CreatedAt, UpdatedAt: project.UpdatedAt, NodeCount: len(document.Nodes), PreviewNodes: preview})
 	}
 	return result, nil
 }