📦 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-jsx-a11y/docs/rules/aria-unsupported-elements.md

@@ -0,0 +1,30 @@
+# jsx-a11y/aria-unsupported-elements
+
+💼 This rule is enabled in the following configs: ☑️ `recommended`, 🔒 `strict`.
+
+<!-- end auto-generated rule header -->
+
+Certain reserved DOM elements do not support ARIA roles, states and properties. This is often because they are not visible, for example `meta`, `html`, `script`, `style`. This rule enforces that these DOM elements do not contain the `role` and/or `aria-*` props.
+
+## Rule details
+
+This rule takes no arguments.
+
+### Succeed
+```jsx
+<!-- Good: the meta element should not be given any ARIA attributes -->
+<meta charset="UTF-8" />
+```
+
+### Fail
+```jsx
+<!-- Bad: the meta element should not be given any ARIA attributes -->
+<meta charset="UTF-8" aria-hidden="false" />
+```
+
+## Accessibility guidelines
+- [WCAG 4.1.2](https://www.w3.org/WAI/WCAG21/Understanding/name-role-value)
+
+### Resources
+- [Chrome Audit Rules, AX_ARIA_12](https://github.com/GoogleChrome/accessibility-developer-tools/wiki/Audit-Rules#ax_aria_12)
+- [DPUB-ARIA roles](https://www.w3.org/TR/dpub-aria-1.0/)