📦 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/readers/async.d.ts

@@ -0,0 +1,10 @@
+import * as fsWalk from '@nodelib/fs.walk';
+import { Entry, ReaderOptions, Pattern } from '../types';
+import Reader from './reader';
+import ReaderStream from './stream';
+export default class ReaderAsync extends Reader<Promise<Entry[]>> {
+    protected _walkAsync: typeof fsWalk.walk;
+    protected _readerStream: ReaderStream;
+    dynamic(root: string, options: ReaderOptions): Promise<Entry[]>;
+    static(patterns: Pattern[], options: ReaderOptions): Promise<Entry[]>;
+}