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/Middleware/SocialPubConfigurations.cs

@@ -19,6 +19,7 @@ using PrivaPub.Federation.Inbox;
 using PrivaPub.Federation.Moderation;
 using PrivaPub.Federation.Inbox.Handlers;
 using PrivaPub.Domain.Content;
+using PrivaPub.Domain.Relationships;
 using PrivaPub.Domain.Social;
 using PrivaPub.Domain.Statuses;
 using PrivaPub.Domain.Timelines;
@@ -72,6 +73,7 @@ namespace PrivaPub.Middleware
 				.AddSingleton<IActivityHandler, UndoHandler>()
 				.AddSingleton<IActivityHandler, LikeHandler>()
 				.AddSingleton<IActivityHandler, AnnounceHandler>()
+				.AddSingleton<IActivityHandler, FlagHandler>()
 				.AddSingleton<IActivityHandler, CreateHandler>()
 				.AddSingleton<IActivityHandler, DeleteHandler>()
 				.AddSingleton<IActivityHandler, UpdateHandler>()
@@ -138,6 +140,8 @@ namespace PrivaPub.Middleware
 				.AddTransient<IGroupUsersService, GroupUsersService>()
 				.AddTransient<IPostsService, PostsService>()
 				.AddTransient<IStatusService, StatusService>()
+				.AddTransient<IRelationshipService, RelationshipService>()
+				.AddTransient<IReportService, ReportService>()
 				.AddTransient<IFollowService, FollowService>()
 				.AddTransient<ITimelineService, TimelineService>()
 				.AddSingleton<AppConfigurationService>()