Mbin joins the pasture; a magazine's own threads and locks are taken

Mbin 1.10.1 runs in the pasture (its image, a messenger worker, a RabbitMQ
of its own, its API limits raised), and peers/mbin_token.py gets mbuser's
token through the authorization-code flow. scenarios/mbin.sh: 24 checks and
one known gap, magazines both ways, titled threads, a Note to a magazine as
a microblog post, comments, favourites and upvotes both ways, a moderator's
lock, unlock and removal, the unfollow and statistics.

What it showed:
- Mbin sends a magazine's threads to its subscribers as the author's Create,
  the magazine as its audience, never announced. A post whose group is
  followed here and lives on the post's own server is now kept as if
  announced; the same from another server is not.
- A moderator's lock is a bare Lock (and Undo{Lock}): LockHandler takes it
  from the post's own server only.
- Mbin takes private messages only as ChatMessage and its actors say
  nothing about it; PrivaPub never decides by a server's software, so this
  stays open as G-0008 for the owner.

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

PrivaPub/Federation/Inbox/Handlers/UndoHandler.cs

@@ -49,6 +49,8 @@ namespace PrivaPub.Federation.Inbox.Handlers
 				undone |= await UndoDislike(inner, innerId, actor, token);
 			if (innerType is null or "Block")
 				undone |= await BlockHandler.Undo(inner, innerId, actor, _localActors, token);
+			if (innerType == "Lock")
+				undone |= await LockHandler.Set(_dbEntities, Id(inner["object"]), actor, locked: false, token);
 			if (innerType is null or "Like" or "EmojiReact")
 				undone |= await _reactions.Withdraw(actor, innerId, inner is JsonObject ? Id(inner["object"]) : default,
 					inner is JsonObject ? Value(inner, "_misskey_reaction") ?? Value(inner, "content") : default, token);