docs(ai): 添加 RAGFlow MCP 部署文档与 AI 栏目整理

- 新增 Windows 11 RAGFlow + MCP 完整部署记录
- 添加 AI 栏目首页与免费模型 API 文档
- 更新 VuePress 配置与 collections 结构
- 添加缓存清理和文档同步脚本

package.json

@@ -13,8 +13,10 @@
   "scripts": {
     "docs:dev": "vuepress dev docs",
     "docs:dev-clean": "vuepress dev docs --clean-cache --clean-temp",
+    "docs:clear-cache": "node scripts/clear-vuepress-cache.mjs",
     "docs:build": "vuepress build docs --clean-cache --clean-temp",
     "docs:verify": "node scripts/verify-site.mjs",
+    "docs:place-ragflow-guide": "node scripts/place-ragflow-guide.mjs",
     "docs:preview": "http-server docs/.vuepress/dist",
     "vp-update": "npx vp-update"
   },