Add prefetch to sort, pagination resets and fix params mutation

[excidence]

This commit fixes:

1. possible blank pages when paginating to the end and applying filters afterwards (e.g. last page + "out of stock" filter), by resetting pagination.
2. mutating the search params in the getSortLink function, briefly breaking SortMenu label (or expected .get() value) until after navigation when useSearchParams is back on track.

Also adds prefetch behavior to SortMenu items.