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/.github/workflows/draft.yml

@@ -0,0 +1,25 @@
+name: Release Drafter
+
+on:
+  push:
+    branches:
+      - main
+
+permissions:
+  contents: read
+  pull-requests: write
+
+jobs:
+  update_release_draft:
+    permissions:
+      # write permission is required to create a github release
+      contents: write
+      # write permission is required for autolabeler
+      # otherwise, read permission is required at least
+      pull-requests: write
+    if: github.repository == 'vbenjs/vue-vben-admin'
+    runs-on: ubuntu-latest
+    steps:
+      - uses: release-drafter/release-drafter@v6
+        env:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}