📦 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/eslint-plugin-import/docs/rules/no-default-export.md

@@ -0,0 +1,65 @@
+# import/no-default-export
+
+<!-- end auto-generated rule header -->
+
+Prohibit default exports. Mostly an inverse of [`prefer-default-export`].
+
+[`prefer-default-export`]: ./prefer-default-export.md
+
+## Rule Details
+
+The following patterns are considered warnings:
+
+```javascript
+// bad1.js
+
+// There is a default export.
+export const foo = 'foo';
+const bar = 'bar';
+export default 'bar';
+```
+
+```javascript
+// bad2.js
+
+// There is a default export.
+const foo = 'foo';
+export { foo as default }
+```
+
+The following patterns are not warnings:
+
+```javascript
+// good1.js
+
+// There is only a single module export and it's a named export.
+export const foo = 'foo';
+```
+
+```javascript
+// good2.js
+
+// There is more than one named export in the module.
+export const foo = 'foo';
+export const bar = 'bar';
+```
+
+```javascript
+// good3.js
+
+// There is more than one named export in the module
+const foo = 'foo';
+const bar = 'bar';
+export { foo, bar }
+```
+
+```javascript
+// export-star.js
+
+// Any batch export will disable this rule. The remote module is not inspected.
+export * from './other-module'
+```
+
+## When Not To Use It
+
+If you don't care if default imports are used, or if you prefer default imports over named imports.