Support numbers as sort values through the NodeJS API

[bglw]

      sort: {
        price: item.price
      },

I get this error:

Pagefind service error when parsing a message: invalid type: integer `69`, expected a string at line 1 column 1297

Originally posted by @stereobooster in https://github.com/CloudCannon/pagefind/discussions/512#discussioncomment-7650017