R4 server pieces: typed admin statistics, DELETE media, accounts by ids, hashtag history in search

Completion program R4 (the client catching up), the server's part.

- /clientapi/admin/statistics/hosts/{host}, /events and /server answer typed views (ViewHostDetail, ViewHostInstance,
  ViewHostDay, ViewInteractionEvent, ViewServerDay in ClientModels) instead of an anonymous object and raw entities:
  the instance's public description, never its raw instance API document; the events without their actor hash. The
  JSON names stay, so lib/interop.sh's stats_check reads them as before.
- DELETE /api/v1/media/{id} (Mastodon 4.4): a persona's own upload goes to the trash while nothing holds it; a posted
  or scheduled one answers 422.
- GET /api/v1/accounts?id[]= (Mastodon 4.3): up to 40 accounts, those that exist.
- /api/v2/search's hashtags carry their week of use (TagsController.History), not an empty history.

Verified: dotnet build PrivaPub.sln -c Release; the pasture: gts 64/64 (statistics included); by hand, an unattached
upload deleted (then 404), a posted one refused (422), accounts by ids, a hashtag's history.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01WpVCoDeM1qUTRp4fXQdfof

PrivaPub/Api/Mastodon/Controllers/SearchController.cs

@@ -77,7 +77,7 @@ namespace PrivaPub.Api.Mastodon.Controllers
 			if (type is null or "statuses" && MyId != default && !q.StartsWith('#') && !Handle().IsMatch(q))
 				results.Statuses = await Words(q, Math.Max(0, offset), Limit(), token);
 			if (type is null or "hashtags" && TagsController.Normalise(q) is var tag && TagsController.IsHashtag(tag))
-				results.Hashtags.Add(new { name = tag, url = $"{_localActors.BaseAddress}/tags/{Uri.EscapeDataString(tag)}", history = Array.Empty<object>() });
+				results.Hashtags.Add(new { name = tag, url = $"{_localActors.BaseAddress}/tags/{Uri.EscapeDataString(tag)}", history = await TagsController.History(_dbEntities, tag, token) });
 			return Json(results);
 		}
 	}