📦 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/es-abstract/2015/InstanceofOperator.js

@@ -0,0 +1,30 @@
+'use strict';
+
+var GetIntrinsic = require('get-intrinsic');
+
+var $TypeError = require('es-errors/type');
+var isObject = require('es-object-atoms/isObject');
+
+var $hasInstance = GetIntrinsic('%Symbol.hasInstance%', true);
+
+var Call = require('./Call');
+var GetMethod = require('./GetMethod');
+var IsCallable = require('./IsCallable');
+var OrdinaryHasInstance = require('./OrdinaryHasInstance');
+var ToBoolean = require('./ToBoolean');
+
+// https://262.ecma-international.org/6.0/#sec-instanceofoperator
+
+module.exports = function InstanceofOperator(O, C) {
+	if (!isObject(O)) {
+		throw new $TypeError('Assertion failed: Type(O) is not Object');
+	}
+	var instOfHandler = $hasInstance ? GetMethod(C, $hasInstance) : void 0;
+	if (typeof instOfHandler !== 'undefined') {
+		return ToBoolean(Call(instOfHandler, C, [O]));
+	}
+	if (!IsCallable(C)) {
+		throw new $TypeError('`C` is not Callable');
+	}
+	return OrdinaryHasInstance(C, O);
+};