chore: add apps/docs clean

Author: xiaoyu2er

apps/docs/package.json

@@ -4,7 +4,9 @@
   "private": true,
   "type": "module",
   "scripts": {
+    "clean": "rm -rf .source",
     "build": "next build",
+    "prebuild": "pnpm run clean",
     "update-search-index": "tsx ./scripts/update-search-index.ts",
     "dev": "next dev --turbo",
     "start": "next start",