restore package.json packageManager setting

what breaks dev on NixOs is that pnpm adds `node_modules/.bin` to the
$PATH.

`rm -rf node_modules/.bin` works as a workaround

package.json

@@ -1,6 +1,7 @@
 {
   "name": "lila",
   "private": true,
+  "packageManager": "pnpm@10.28.0",
   "engines": {
     "node": ">=24",
     "pnpm": "10"