Search needs a web server. This page was opened straight from disk (file://), and browsers refuse to fetch the search index over that protocol. Site-wide links are absolute too, so they will not work either. Serve the build instead:

npm run preview

Any static server works, for example npx serve dist or python3 -m http.server -d dist.

The search index is generated at build time, so search is unavailable under npm run dev. Run npm run build, then npm run preview.