chore: relax engines.pnpm to >=9.4 for Vercel compatibility

Author: dzienisz

package.json

@@ -123,7 +123,7 @@
   "engines": {
     "node": "24.x",
     "npm": ">=10.8",
-    "pnpm": ">=11.20.0"
+    "pnpm": ">=9.4"
   },
   "packageManager": "pnpm@11.20.0+sha512.951afc50fc337a7a862548bb52a33cbfa7f0ee84d5bd6fe4b05042ec5b35c078cd402e3f77c9a4ccaeb00f9716ae140edd0c2c22ffa4b1b1fd03336daf75460c"
 }