📦 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-named-default.md

@@ -0,0 +1,36 @@
+# import/no-named-default
+
+<!-- end auto-generated rule header -->
+
+Reports use of a default export as a locally named import.
+
+Rationale: the syntax exists to import default exports expressively, let's use it.
+
+Note that type imports, as used by [Flow], are always ignored.
+
+[Flow]: https://flow.org/
+
+## Rule Details
+
+Given:
+
+```js
+// foo.js
+export default 'foo';
+export const bar = 'baz';
+```
+
+...these would be valid:
+
+```js
+import foo from './foo.js';
+import foo, { bar } from './foo.js';
+```
+
+...and these would be reported:
+
+```js
+// message: Using exported name 'bar' as identifier for default export.
+import { default as foo } from './foo.js';
+import { default as foo, bar } from './foo.js';
+```