📦 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-iterator-helpers/README.md

@@ -0,0 +1,112 @@
+# es-iterator-helpers <sup>[![Version Badge][npm-version-svg]][package-url]</sup>
+
+[![github actions][actions-image]][actions-url]
+[![coverage][codecov-image]][codecov-url]
+[![License][license-image]][license-url]
+[![Downloads][downloads-image]][downloads-url]
+
+[![npm badge][npm-badge-png]][package-url]
+
+An ESnext spec-compliant sync iterator helpers shim/polyfill/replacement that works as far down as ES3.
+
+This package implements the [es-shim API](https://github.com/es-shims/api) “multi” interface. It works in an ES3-supported environment and complies with the [iterator helpers spec](https://tc39.es/proposal-iterator-helpers/) and the [iterator sequencing spec](https://tc39.es/proposal-iterator-sequencing/).
+
+Because the `Iterator.prototype` methods depend on a receiver (the `this` value), the main export in each subdirectory takes the iterator to operate on as the first argument.
+
+The main export of the package itself is simply an array of the available directory names. It’s sole intended use is for build tooling and testing.
+
+## Supported things
+
+ - [`Iterator` constructor](https://tc39.es/proposal-iterator-helpers/#sec-iterator-constructor)
+ - [`Iterator.prototype`](https://tc39.es/proposal-iterator-helpers/#sec-iterator.prototype)
+ - [`Iterator.concat`](https://tc39.es/proposal-iterator-sequencing/)
+ - [`Iterator.from`](https://tc39.es/proposal-iterator-helpers/#sec-iterator.from)
+ - [`Iterator.zip`](https://tc39.es/proposal-joint-iteration/#sec-iterator.zip)
+ - [`Iterator.zipKeyed`](https://tc39.es/proposal-joint-iteration/#sec-iterator.zipkeyed)
+ - [`Iterator.prototype.constructor`](https://tc39.es/proposal-iterator-helpers/#sec-iteratorprototype.constructor)
+ - [`Iterator.prototype.drop`](https://tc39.es/proposal-iterator-helpers/#sec-iteratorprototype.drop)
+ - [`Iterator.prototype.every`](https://tc39.es/proposal-iterator-helpers/#sec-iteratorprototype.every)
+ - [`Iterator.prototype.filter`](https://tc39.es/proposal-iterator-helpers/#sec-iteratorprototype.filter)
+ - [`Iterator.prototype.find`](https://tc39.es/proposal-iterator-helpers/#sec-iteratorprototype.find)
+ - [`Iterator.prototype.flatMap`](https://tc39.es/proposal-iterator-helpers/#sec-iteratorprototype.flatmap)
+ - [`Iterator.prototype.forEach`](https://tc39.es/proposal-iterator-helpers/
+ #sec-iteratorprototype.foreach)
+ - [`Iterator.prototype.includes`](https://tc39.es/proposal-iterator-includes/)
+ - [`Iterator.prototype.map`](https://tc39.es/proposal-iterator-helpers/#sec-iteratorprototype.map)
+ - [`Iterator.prototype.reduce`](https://tc39.es/proposal-iterator-helpers/#sec-iteratorprototype.reduce)
+ - [`Iterator.prototype.some`](https://tc39.es/proposal-iterator-helpers/#sec-iteratorprototype.some)
+ - [`Iterator.prototype.take`](https://tc39.es/proposal-iterator-helpers/#sec-iteratorprototype.take)
+ - [`Iterator.prototype.toArray`](https://tc39.es/proposal-iterator-helpers/#sec-iteratorprototype.toarray)
+
+## Environments where this is needed
+
+ - node v22, Chrome >= v122: has a [bug](https://issues.chromium.org/issues/336839115)
+ - node < v22, Chrome < v122, Safari <= v17.1, Firefox <= v125: not implemented
+ - all environments lack Iterator.concat, Iterator.zip, Iterator.zipKeyed
+
+## Getting started
+
+```sh
+npm install --save es-iterator-helpers
+```
+
+## Usage/Examples
+
+Using explicit imports:
+
+```js
+const map = require('es-iterator-helpers/Iterator.prototype.map');
+const toArray = require('es-iterator-helpers/Iterator.prototype.toArray');
+const assert = require('assert');
+
+const iterator = [1, 2, 3].values();
+
+const mapped = map(iterator, (x) => x + 10);
+assert.deepEqual(
+	mapped.next(),
+    {
+        done: false,
+        value: 11,
+    }
+);
+assert.deepEqual(
+    toArray(mapped),
+    [12, 13]
+);
+```
+
+Shim using `require`:
+
+```js
+require('es-iterator-helpers/auto'); // shim all of the methods
+
+require('es-iterator-helpers/Iterator.prototype.map/auto'); // shim the “map” method
+```
+
+Shim using `import` syntax:
+
+[](#preventEval)
+```js
+import 'es-iterator-helpers/auto'; // shim all of the methods
+
+import 'es-iterator-helpers/Iterator.prototype.map/auto'; // shim the “map” method
+```
+
+## Tests
+Simply clone the repo, `npm install`, and run `npm test`
+
+[package-url]: https://npmjs.org/package/es-iterator-helpers
+[npm-version-svg]: https://versionbadg.es/es-shims/iterator-helpers.svg
+[deps-svg]: https://david-dm.org/es-shims/iterator-helpers.svg
+[deps-url]: https://david-dm.org/es-shims/iterator-helpers
+[dev-deps-svg]: https://david-dm.org/es-shims/iterator-helpers/dev-status.svg
+[dev-deps-url]: https://david-dm.org/es-shims/iterator-helpers#info=devDependencies
+[npm-badge-png]: https://nodei.co/npm/es-iterator-helpers.png?downloads=true&stars=true
+[license-image]: https://img.shields.io/npm/l/es-iterator-helpers.svg
+[license-url]: LICENSE
+[downloads-image]: https://img.shields.io/npm/dm/es-iterator-helpers.svg
+[downloads-url]: https://npm-stat.com/charts.html?package=es-iterator-helpers
+[codecov-image]: https://codecov.io/gh/es-shims/iterator-helpers/branch/main/graphs/badge.svg
+[codecov-url]: https://app.codecov.io/gh/es-shims/iterator-helpers/
+[actions-image]: https://img.shields.io/github/check-runs/es-shims/iterator-helpers/main
+[actions-url]: https://github.com/es-shims/iterator-helpers/actions