Add search filters #2

Carried over from TODO.md. Expose deviantart search filters in the search UI.

Investigated on 2026-09-12 from the public instance's egress with a guest session. DeviantArt's guest search API (dabrowse/search/all) ignores every order value the site's own search page uses (most-recent, popular-all-time, popular-1-week, popular-1-month): results are identical in each case. The site's dedicated dabrowse/search/deviations endpoint answers a guest with a redirect. So there is nothing upstream to expose as a filter.

Left open in case a guest-accessible ordering appears. The only filters possible today are client-side narrowing of what the instance already fetched (hide mature, hide AI per request), which is a different, smaller feature.

Closing: DeviantArt offers guests no ordering or filtering on search, per the investigation above. Reopen if that changes.