[Feature] Easy category scraping

In other scrapers, they use a fancy `/page/preview` endpoint that lets them generate lists of all the pages in the category they want.
- [ref](https://github.com/NullEnt1ty/gmod-wiki-scraper/blob/master/src/wiki-api-client.ts#L28)
- [ref](https://github.com/NullEnt1ty/gmod-wiki-scraper/blob/master/src/wiki-scraper.ts#L178)

It would be nice if we could support this 1-1, though I worry because the `category` thing appears to be an internal property that isn't exposed on the frontend.

We can potentially query these ourselves during buildtime and store them - same thing with the tags.

Then, we just store the resulting .json in `public/` or upload to R2