Blocks, mutes, bookmarks, pins and reports

- Blocks are per persona and never federate (a Block activity would tell
  the other server who blocked whom): the blocked account is removed as a
  follower, with a Reject{Follow} if it is remote, unfollowed, cleared from
  home and notifications, and refused with Reject if it follows again.
- Mutes (optionally timed, optionally sparing notifications) and per-
  persona domain blocks keep authors out of home timelines, notifications
  and every status list the API returns; the boosts of a hidden author's
  posts are hidden too.
- Bookmarks and pins (at most five, public or unlisted, own posts) with
  their Mastodon endpoints and flags; pinned posts are the actor's
  `featured` collection at /trophies, and `featuredTags` points at
  /tattoos.
- Reports: /api/v1/reports stores the report and, when forwarding to a
  remote account, sends Flag from the instance actor, so the reporting
  persona is never named to the other server. An inbound Flag about a local
  persona or its posts becomes a report; moderators list and resolve them
  under /clientapi/moderator/reports.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_012CzABvBkbcFqoHdmi8b9WB

PrivaPub.Tests/Support/Harness.cs

@@ -5,6 +5,7 @@ using Microsoft.Extensions.Logging.Abstractions;
 using MongoDB.Entities;
 
 using PrivaPub.Domain.Content;
+using PrivaPub.Domain.Relationships;
 using PrivaPub.Domain.Social;
 using PrivaPub.Domain.Statuses;
 using PrivaPub.Domain.Timelines;
@@ -51,7 +52,8 @@ namespace PrivaPub.Tests.Support
 				new AnnounceHandler(Db, Local, RemotePosts, Fanout),
 				new CreateHandler(Db, Local, Remote, Delivery, new NoBlocks(), Fanout, RemotePosts),
 				new DeleteHandler(Db, Local, Remote, Delivery),
-				new UpdateHandler(Db, Local, Remote)
+				new UpdateHandler(Db, Local, Remote),
+				new FlagHandler(Db, Local)
 			}, NullLogger<InboxProcessor>.Instance);
 			Follows = new FollowService(Db, Local, Remote, Delivery, new KeyLocalizer<GenericRes>(), NullLogger<FollowService>.Instance);
 			Content = new ContentRenderer(Local, Remote);
@@ -59,6 +61,8 @@ namespace PrivaPub.Tests.Support
 			Statuses = new StatusService(Db, Local, Remote, Delivery, Content, Outbox, Fanout);
 			Posts = new PostsService(Db, Local, Statuses, new KeyLocalizer<GenericRes>(), NullLogger<PostsService>.Instance);
 			Timelines = new TimelineService(Db, new KeyLocalizer<GenericRes>());
+			Relationships = new RelationshipService(Db, Follows, Delivery);
+			Reports = new ReportService(Db, Local, Delivery);
 		}
 
 		public Peer Peer { get; }
@@ -77,6 +81,8 @@ namespace PrivaPub.Tests.Support
 		public Fanout Fanout { get; }
 		public RemotePosts RemotePosts { get; }
 		public TimelineService Timelines { get; }
+		public RelationshipService Relationships { get; }
+		public ReportService Reports { get; }
 
 		public async Task FollowedBy(LocalActor local, RemoteActor follower) =>
 			await DB.Default.SaveAsync(new Follower