* Refactor the paginator into a ViewComponent.
* Fix inconsistent spacing between paginator items.
* Fix a bug where the sequential paginator generated the wrong next /
previous page links in the <link rel="{next|prev}"> tags in the <head>.
* Always include the final page as a hidden html element, so that it can
be unhidden with custom CSS.
* Make it easier to change the pagination window.
Refactor CSS to use standard Tailwind-style utility classes instead of
ad-hoc rules. This eliminates a lot of single-purpose rules for specific
UI elements and standardizes margins to be more consistent throughout
the site.
Utility classes are defined manually on an as-needed basis instead of
importing Tailwind as a whole. Naming conventions mostly follow
Tailwind's conventions, otherwise they follow Bootstrap.
* https://tailwindcss.com/docs/
* https://getbootstrap.com/docs/5.0/utilities/spacing/
Add <link rel="prev"> and <link rel="next"> tags to the forum topic show
page, the pool show page, and the favgroup show page.
This is kind of useless now since Google hasn't used these tags for SEO
for years ([1]), and userscripts can use `#paginator-next` and
`#paginator-prev` to find the next/prev pages, but whatever.
[1]: https://yoast.com/google-doesnt-use-rel-prev-next-for-pagination
