📦 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-relative-packages.md

@@ -0,0 +1,69 @@
+# import/no-relative-packages
+
+🔧 This rule is automatically fixable by the [`--fix` CLI option](https://eslint.org/docs/latest/user-guide/command-line-interface#--fix).
+
+<!-- end auto-generated rule header -->
+
+Use this rule to prevent importing packages through relative paths.
+
+It's useful in Yarn/Lerna workspaces, where it's possible to import a sibling package using `../package` relative path, while direct `package` is the correct one.
+
+## Examples
+
+Given the following folder structure:
+
+```pt
+my-project
+├── packages
+│   ├── foo
+│   │   ├── index.js
+│   │   └── package.json
+│   └── bar
+│       ├── index.js
+│       └── package.json
+└── entry.js
+```
+
+And the .eslintrc file:
+
+```json
+{
+  ...
+  "rules": {
+    "import/no-relative-packages": "error"
+  }
+}
+```
+
+The following patterns are considered problems:
+
+```js
+/**
+ *  in my-project/packages/foo.js
+ */
+
+import bar from '../bar'; // Import sibling package using relative path
+import entry from '../../entry.js'; // Import from parent package using relative path
+
+/**
+ *  in my-project/entry.js
+ */
+
+import bar from './packages/bar'; // Import child package using relative path
+```
+
+The following patterns are NOT considered problems:
+
+```js
+/**
+ *  in my-project/packages/foo.js
+ */
+
+import bar from 'bar'; // Import sibling package using package name
+
+/**
+ *  in my-project/entry.js
+ */
+
+import bar from 'bar'; // Import sibling package using package name
+```