Pagination breaks on blog when using `base` prefix

Steps to reproduce:

1. Generate a new project `npm create astro@latest -- --template onwidget/astrowind`
2. Edit `src/config.yaml`, set `site.base: /anything`, change `app.blog.postsPerPage: 4`
3. open http://localhost:4321/anything/blog, scroll to bottom and click "Next Page"
4. Get a 404, see `http://localhost:4321/anything/anything/blog/2` in URL