📦 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/serialize-javascript/package.json

@@ -0,0 +1,36 @@
+{
+  "name": "serialize-javascript",
+  "version": "6.0.2",
+  "description": "Serialize JavaScript to a superset of JSON that includes regular expressions and functions.",
+  "main": "index.js",
+  "scripts": {
+    "benchmark": "node -v && node test/benchmark/serialize.js",
+    "test": "nyc --reporter=lcov mocha test/unit"
+  },
+  "repository": {
+    "type": "git",
+    "url": "git+https://github.com/yahoo/serialize-javascript.git"
+  },
+  "keywords": [
+    "serialize",
+    "serialization",
+    "javascript",
+    "js",
+    "json"
+  ],
+  "author": "Eric Ferraiuolo <edf@ericf.me>",
+  "license": "BSD-3-Clause",
+  "bugs": {
+    "url": "https://github.com/yahoo/serialize-javascript/issues"
+  },
+  "homepage": "https://github.com/yahoo/serialize-javascript",
+  "devDependencies": {
+    "benchmark": "^2.1.4",
+    "chai": "^4.1.0",
+    "mocha": "^10.0.0",
+    "nyc": "^15.0.0"
+  },
+  "dependencies": {
+    "randombytes": "^2.1.0"
+  }
+}