refactor: 将 WebUI 源码纳入仓库,移除打包产物

- 新增 webui/ 前端源码目录（React+Vite+TypeScript+Tailwind）
- 删除 api/webui/ 中旧的打包静态资源
- 更新 .gitignore 忽略 api/webui/ 构建输出和 webui/node_modules
- 更新 README 增加前端构建说明

webui/package.json

@@ -0,0 +1,45 @@
+{
+  "name": "mediacrawler-webui",
+  "private": true,
+  "version": "1.0.0",
+  "type": "module",
+  "scripts": {
+    "dev": "vite",
+    "build": "tsc -b && vite build",
+    "lint": "eslint .",
+    "preview": "vite preview"
+  },
+  "dependencies": {
+    "@radix-ui/react-accordion": "^1.2.2",
+    "@radix-ui/react-dialog": "^1.1.4",
+    "@radix-ui/react-label": "^2.1.1",
+    "@radix-ui/react-scroll-area": "^1.2.2",
+    "@radix-ui/react-select": "^2.1.4",
+    "@radix-ui/react-slot": "^1.1.1",
+    "@radix-ui/react-tabs": "^1.1.2",
+    "@tanstack/react-query": "^5.62.7",
+    "axios": "^1.7.9",
+    "class-variance-authority": "^0.7.1",
+    "clsx": "^2.1.1",
+    "i18next": "^25.7.3",
+    "i18next-browser-languagedetector": "^8.2.0",
+    "lucide-react": "^0.468.0",
+    "react": "^18.3.1",
+    "react-dom": "^18.3.1",
+    "react-i18next": "^16.5.0",
+    "sonner": "^1.7.1",
+    "tailwind-merge": "^2.6.0",
+    "zustand": "^5.0.2"
+  },
+  "devDependencies": {
+    "@types/react": "^18.3.16",
+    "@types/react-dom": "^18.3.5",
+    "@vitejs/plugin-react": "^4.3.4",
+    "autoprefixer": "^10.4.20",
+    "postcss": "^8.4.49",
+    "tailwindcss": "^3.4.17",
+    "tailwindcss-animate": "^1.0.7",
+    "typescript": "~5.6.2",
+    "vite": "^6.0.3"
+  }
+}