📦 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/tailwindcss/stubs/.npmignore

@@ -0,0 +1 @@
+!*

frontend/node_modules/tailwindcss/stubs/.prettierrc.json

@@ -0,0 +1,6 @@
+{
+  "printWidth": 120,
+  "semi": false,
+  "singleQuote": true,
+  "trailingComma": "es5"
+}

frontend/node_modules/tailwindcss/stubs/config.simple.js

@@ -0,0 +1,7 @@
+module.exports = {
+  content: [],
+  theme: {
+    extend: {},
+  },
+  plugins: [],
+}

frontend/node_modules/tailwindcss/stubs/postcss.config.cjs

@@ -0,0 +1,6 @@
+module.exports = {
+  plugins: {
+    tailwindcss: {},
+    autoprefixer: {},
+  },
+}

frontend/node_modules/tailwindcss/stubs/postcss.config.js

@@ -0,0 +1,6 @@
+export default {
+  plugins: {
+    tailwindcss: {},
+    autoprefixer: {},
+  },
+}

frontend/node_modules/tailwindcss/stubs/tailwind.config.cjs

@@ -0,0 +1,2 @@
+/** @type {import('tailwindcss').Config} */
+module.exports = __CONFIG__

frontend/node_modules/tailwindcss/stubs/tailwind.config.js

@@ -0,0 +1,2 @@
+/** @type {import('tailwindcss').Config} */
+export default __CONFIG__

frontend/node_modules/tailwindcss/stubs/tailwind.config.ts

@@ -0,0 +1,3 @@
+import type { Config } from 'tailwindcss'
+
+export default __CONFIG__ satisfies Config