📦 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/launch-editor/package.json

@@ -0,0 +1,24 @@
+{
+  "name": "launch-editor",
+  "version": "2.13.2",
+  "description": "launch editor from node.js",
+  "main": "index.js",
+  "repository": {
+    "type": "git",
+    "url": "git+https://github.com/yyx990803/launch-editor.git"
+  },
+  "keywords": [
+    "launch",
+    "editor"
+  ],
+  "author": "Evan You",
+  "license": "MIT",
+  "bugs": {
+    "url": "https://github.com/yyx990803/launch-editor/issues"
+  },
+  "homepage": "https://github.com/yyx990803/launch-editor#readme",
+  "dependencies": {
+    "picocolors": "^1.1.1",
+    "shell-quote": "^1.8.3"
+  }
+}