fix: update next-mdx-remote to v6 (CVE-2026-0969)

Also restore missing pnpm-workspace.yaml

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: vklimontovich

packages/website/package.json

@@ -26,7 +26,7 @@
     "lucide-react": "^0.563.0",
     "next": "^15.0.0",
     "next-auth": "^5.0.0-beta.30",
-    "next-mdx-remote": "^5.0.0",
+    "next-mdx-remote": "^6.0.0",
     "@nextlytics/core": "workspace:*",
     "react": "^19.0.0",
     "react-dom": "^19.0.0",