feat: 添加完整的前端管理系统 (VbenAdmin)

- 添加基于 VbenAdmin + Vue3 + Element Plus 的前端管理系统
- 包含完整的 UI 组件库和工具链
- 支持多应用架构 (web-ele, backend-mock, playground)
- 包含完整的开发规范和配置
- 修复 admin 目录的子模块问题，确保正确提交

admin/packages/effects/plugins/src/motion/index.ts

@@ -0,0 +1,8 @@
+export * from './types';
+
+export {
+  MotionComponent as Motion,
+  MotionDirective,
+  MotionGroupComponent as MotionGroup,
+  MotionPlugin,
+} from '@vueuse/motion';

admin/packages/effects/plugins/src/motion/types.ts

@@ -0,0 +1,26 @@
+export const MotionPresets = [
+  'fade',
+  'fadeVisible',
+  'fadeVisibleOnce',
+  'rollBottom',
+  'rollLeft',
+  'rollRight',
+  'rollTop',
+  'rollVisibleBottom',
+  'rollVisibleLeft',
+  'rollVisibleRight',
+  'rollVisibleTop',
+  'pop',
+  'popVisible',
+  'popVisibleOnce',
+  'slideBottom',
+  'slideLeft',
+  'slideRight',
+  'slideTop',
+  'slideVisibleBottom',
+  'slideVisibleLeft',
+  'slideVisibleRight',
+  'slideVisibleTop',
+] as const;
+
+export type MotionPreset = (typeof MotionPresets)[number];