📦 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/fast-glob/out/utils/index.d.ts

@@ -0,0 +1,8 @@
+import * as array from './array';
+import * as errno from './errno';
+import * as fs from './fs';
+import * as path from './path';
+import * as pattern from './pattern';
+import * as stream from './stream';
+import * as string from './string';
+export { array, errno, fs, path, pattern, stream, string };