📦 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/tapable/lib/AsyncSeriesLoopHook.js

@@ -0,0 +1,37 @@
+/*
+	MIT License http://www.opensource.org/licenses/mit-license.php
+	Author Tobias Koppers @sokra
+*/
+"use strict";
+
+const Hook = require("./Hook");
+const HookCodeFactory = require("./HookCodeFactory");
+
+class AsyncSeriesLoopHookCodeFactory extends HookCodeFactory {
+	content({ onError, onDone }) {
+		return this.callTapsLooping({
+			onError: (i, err, next, doneBreak) => onError(err) + doneBreak(true),
+			onDone
+		});
+	}
+}
+
+const factory = new AsyncSeriesLoopHookCodeFactory();
+
+function COMPILE(options) {
+	factory.setup(this, options);
+	return factory.create(options);
+}
+
+function AsyncSeriesLoopHook(args = [], name = undefined) {
+	const hook = new Hook(args, name);
+	hook.constructor = AsyncSeriesLoopHook;
+	hook.compile = COMPILE;
+	hook._call = undefined;
+	hook.call = undefined;
+	return hook;
+}
+
+AsyncSeriesLoopHook.prototype = null;
+
+module.exports = AsyncSeriesLoopHook;