📦 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/is-module/.npmignore

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+test

frontend/node_modules/is-module/README.md

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+# Is Module
+
+Check whether a source string looks like an ES6 module.
+This doesn't actually execute the code,
+and doesn't check other module types.
+So source strings without any module loaders returns `false`.
+
+This is just what I need from https://github.com/yahoo/js-module-formats, which actually executes the sauce string in a subcontext.
+
+## API
+
+```js
+var isES6Module = require('is-module');
+
+console.log(isES6Module('import * from "emitter";')) // => true
+```
+
+## License
+
+(The MIT License)
+
+Copyright (c) 2014 segmentio <team@segment.io>
+
+Permission is hereby granted, free of charge, to any person obtaining
+a copy of this software and associated documentation files (the
+'Software'), to deal in the Software without restriction, including
+without limitation the rights to use, copy, modify, merge, publish,
+distribute, sublicense, and/or sell copies of the Software, and to
+permit persons to whom the Software is furnished to do so, subject to
+the following conditions:
+
+The above copyright notice and this permission notice shall be
+included in all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED 'AS IS', WITHOUT WARRANTY OF ANY KIND,
+EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
+IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
+CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
+TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
+SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

frontend/node_modules/is-module/component.json

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+{
+  "name": "is-module",
+  "description": "check if a source string is an es6 module",
+  "keywords": ["es6", "module", "modules"],
+  "version": "1.0.0",
+  "license": "MIT",
+  "repo": "component/is-module",
+  "scripts": [
+    "index.js"
+  ]
+}

frontend/node_modules/is-module/index.js

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+
+// no idea what these regular expressions do,
+// but i extracted it from https://github.com/yahoo/js-module-formats/blob/master/index.js#L18
+var ES6ImportExportRegExp = /(?:^\s*|[}{\(\);,\n]\s*)(import\s+['"]|(import|module)\s+[^"'\(\)\n;]+\s+from\s+['"]|export\s+(\*|\{|default|function|var|const|let|[_$a-zA-Z\xA0-\uFFFF][_$a-zA-Z0-9\xA0-\uFFFF]*))/;
+
+var ES6AliasRegExp = /(?:^\s*|[}{\(\);,\n]\s*)(export\s*\*\s*from\s*(?:'([^']+)'|"([^"]+)"))/;
+
+module.exports = function (sauce) {
+  return ES6ImportExportRegExp.test(sauce)
+    || ES6AliasRegExp.test(sauce);
+};

frontend/node_modules/is-module/package.json

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+{
+  "name": "is-module",
+  "description": "check if a source string is an es6 module",
+  "keywords": ["es6", "module", "modules"],
+  "version": "1.0.0",
+  "author": {
+    "name": "Jonathan Ong",
+    "email": "me@jongleberry.com",
+    "url": "http://jongleberry.com",
+    "twitter": "https://twitter.com/jongleberry"
+  },
+  "license": "MIT",
+  "repository": "component/is-module",
+  "devDependencies": {
+    "mocha": "*"
+  },
+  "scripts": {
+    "test": "mocha --reporter spec --bail"
+  }
+}