R4 the client catches up: follow requests, followers, downvotes, dismissing, filtering a post, quote policies, statistics in detail

Follow requests answered on the persona's own profile and from the Notifications tab; its followers and the accounts it
follows listed there, a follower removed (asked first). Downvotes on threadiverse posts, after the public-vote notice.
A notification dismissed from its line. "Filter this post" from a card's menu, and the Filters page showing the posts a
filter holds. Who may quote the persona's own posts, and revoking a quote of one. Statistics: a server in detail with
"describe again", the ledger's events, the server's own days. The composer deletes an upload taken out before posting.
MediaType.Documents goes.

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

Services/TimelineService.cs

@@ -156,6 +156,14 @@ namespace decePubClient.Services
 			return response.IsSuccessStatusCode ? new WebResult() : await response.Content.ReadWebResult(response.StatusCode, localizer, cancellationToken);
 		}
 
+		/// <summary>Dismisses a group of notifications (/api/v2/notifications/:group_key/dismiss): every notification of
+		/// the group goes; an ungrouped one's key is ungrouped-{id}.</summary>
+		public async Task<WebResult> DismissNotification(string groupKey, CancellationToken cancellationToken = default)
+		{
+			using var response = await httpService.Post(APIs.Mastodon.POST_M_DismissNotificationGroup(groupKey), cancellationToken: cancellationToken);
+			return response.IsSuccessStatusCode ? new WebResult() : await response.Content.ReadWebResult(response.StatusCode, localizer, cancellationToken);
+		}
+
 		/// <summary>Moves the notifications marker to the newest one seen, which reads everything up to it.</summary>
 		public async Task<WebResult> ReadNotificationsUpTo(string notificationId, CancellationToken cancellationToken = default)
 		{