📦 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/@babel/plugin-transform-react-jsx-development/lib/index.js

@@ -0,0 +1,10 @@
+"use strict";
+
+Object.defineProperty(exports, "__esModule", {
+  value: true
+});
+exports.default = void 0;
+var _development = require("@babel/plugin-transform-react-jsx/lib/development");
+var _default = exports.default = _development.default;
+
+//# sourceMappingURL=index.js.map

frontend/node_modules/@babel/plugin-transform-react-jsx-development/lib/index.js.map

@@ -0,0 +1 @@
+{"version":3,"names":["_development","require","_default","exports","default","plugin"],"sources":["../src/index.ts"],"sourcesContent":["/* eslint-disable @babel/development/plugin-name */\n\nimport plugin from \"@babel/plugin-transform-react-jsx/lib/development\";\n// We need to explicitly annotate this export because\n// @babel/plugin-transform-react-jsx/lib/development has no type definitions\n// (it's not a public entry point)\n// eslint-disable-next-line @typescript-eslint/no-unnecessary-type-assertion\nexport default plugin as typeof import(\"@babel/plugin-transform-react-jsx\").default;\n"],"mappings":";;;;;;AAEA,IAAAA,YAAA,GAAAC,OAAA;AAAuE,IAAAC,QAAA,GAAAC,OAAA,CAAAC,OAAA,GAKxDC,oBAAM","ignoreList":[]}