feat: update engine classes exports

Author: liujuping

packages/engine/src/modules/classes.ts

@@ -1,4 +1,4 @@
-import {
+export {
   Project,
   Skeleton,
   DocumentModel,
@@ -12,20 +12,5 @@ import {
   SimulatorHost,
   SkeletonItem,
 } from '@alilc/lowcode-shell';
-import { Node as InnerNode } from '@alilc/lowcode-designer';
+export { Node as InnerNode } from '@alilc/lowcode-designer';
 
-export default {
-  Project,
-  Skeleton,
-  DocumentModel,
-  Node,
-  NodeChildren,
-  History,
-  SettingPropEntry,
-  SettingTopEntry,
-  InnerNode,
-  Selection,
-  Prop,
-  SimulatorHost,
-  SkeletonItem,
-};