📦 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/array-includes/test/implementation.js

@@ -0,0 +1,20 @@
+'use strict';
+
+var implementation = require('../implementation');
+var callBind = require('call-bind');
+var test = require('tape');
+var hasStrictMode = require('has-strict-mode')();
+var runTests = require('./tests');
+
+test('as a function', function (t) {
+	t.test('bad array/this value', { skip: !hasStrictMode }, function (st) {
+		/* eslint no-useless-call: 0 */
+		st['throws'](function () { implementation.call(undefined); }, TypeError, 'undefined is not an object');
+		st['throws'](function () { implementation.call(null); }, TypeError, 'null is not an object');
+		st.end();
+	});
+
+	runTests(callBind(implementation), t);
+
+	t.end();
+});