📦 添加虚拟环境和启动脚本

新增:
- backend/venv/ - Python 虚拟环境
- backend/start.sh - 启动脚本（使用虚拟环境）
- backend/requirements.txt - 依赖列表
- .gitignore - 忽略虚拟环境和缓存文件

说明:
- 每个项目使用独立虚拟环境
- 避免依赖冲突
- 启动脚本自动创建和激活虚拟环境

frontend/node_modules/is-root/readme.md

@@ -0,0 +1,35 @@
+# is-root [![Build Status](https://travis-ci.org/sindresorhus/is-root.svg?branch=master)](https://travis-ci.org/sindresorhus/is-root)
+
+> Check if the process is running as root user, for example, one started with `sudo`
+
+
+## Install
+
+```
+$ npm install is-root
+```
+
+
+## Usage
+
+```
+$ sudo node index.js
+```
+
+```js
+// index.js
+const isRoot = require('is-root');
+
+isRoot();
+//=> true
+```
+
+
+## Related
+
+- [is-elevated](https://github.com/sindresorhus/is-elevated) - Check if the process is running with elevated privileges *(cross-platform)*
+
+
+## License
+
+MIT © [Sindre Sorhus](https://sindresorhus.com)