Pins across servers, both ways

An account elsewhere that pins or unpins one of its posts (Add or Remove on its `featured`) now shows those pins on its
profile here (`pinned=true`), in its order and its public posts only; a community's announce of a moderator's Add does
the same for the community. The `featured` collection itself is read with the account's counts, at most once a day, so
pins made before PrivaPub ever saw an account show too. Any other target (Smithereen's wall, a community's moderators)
is dropped. A persona's pin and unpin go to the post's audience as Add and Remove on /trophies, as Mastodon sends them.

Checked live against Mastodon (scenarios/pins.sh, 8 checks). The town's checker learnt three peer rules from the
village: Misskey and Sharkey keep a forwarded reply only with its author's LD signature (only Mastodon signs), they
count no renote by a bot, and Mastodon never sees a Lemmy vote on a post in a community. The village of 2026-10-05
checks clean, 2454 of 2454.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01LsXgEaXee4GCU1hwYgPJXw

PrivaPub.Tests/Http/MastodonAccountsTests.cs

@@ -183,6 +183,33 @@ namespace PrivaPub.Tests.Http
 			Assert.Contains(alice.Id, (await alice.Client.Get($"/api/v1/accounts/search?q={alice.UserName}")).Ok().Ids);
 		}
 
+		// an account elsewhere: what it features, in its order, its public posts only
+		[Fact]
+		public async Task A_remote_accounts_pinned_statuses_are_what_it_features()
+		{
+			var alice = await _host.Mastodon("alice");
+			var (bob, bobId) = await Remote();
+			Post Held(string text, PostVisibility visibility) => new()
+			{
+				ObjectURI = $"{bob.Id}/statuses/{Guid.NewGuid():N}", ActorURI = bob.Id, AuthorAccountId = bobId, IsFederatedCopy = true,
+				Visibility = visibility, ContentHtml = $"<p>{text}</p>", CreationDate = DateTime.UtcNow, UpdateDate = DateTime.UtcNow
+			};
+			var first = Held("first pin", PostVisibility.Public);
+			var second = Held("second pin", PostVisibility.Unlisted);
+			var hidden = Held("for followers", PostVisibility.FollowersOnly);
+			await DB.Default.SaveAsync(new[] { first, second, hidden }, Token);
+			await DB.Default.SaveAsync(new[]
+			{
+				new RemoteFeatured { ActorURI = bob.Id, ObjectURI = second.ObjectURI, PostId = second.ID, Position = 1 },
+				new RemoteFeatured { ActorURI = bob.Id, ObjectURI = hidden.ObjectURI, PostId = hidden.ID, Position = 2 },
+				new RemoteFeatured { ActorURI = bob.Id, ObjectURI = first.ObjectURI, PostId = first.ID, Position = 0 }
+			}, Token);
+
+			var pinned = (await alice.Client.Get($"/api/v1/accounts/{bobId}/statuses?pinned=true")).Ok();
+
+			Assert.Equal(new[] { first.ID, second.ID }, pinned.Ids);
+		}
+
 		[Fact]
 		public async Task Account_statuses_filter_pins_replies_reblogs_media_and_tags_and_page_both_ways()
 		{