A community's moderators lock threads and ban members

Lemmy's moderation reached PrivaPub only as removals. Now a remote
community's lock and ban, relayed in its Announce, apply too:

- a lock (Announce{Lock}, or commentsEnabled false on the post) refuses
  replies to the thread, ours included, until Undo{Lock}; statuses say so
  in privapub.locked;
- a ban of a persona (Announce{Block} with the community as target, or the
  moderator's own Block sent straight to us, which is the community's ban
  and never the moderator's block of the persona) shows as blocked_by on
  the community and refuses the persona's posts and replies there until
  the Undo.

The Lemmy scenario's removal was an expected failure only because it gave
up before Lemmy's 30-second batch; it now waits, and checks the lock and
the ban live (Lemmy refuses a lock or an unban without a reason): 29
checks, none expected to fail. G-0003 and G-0006 are closed.

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

PrivaPub/Models/Post/Post.cs

@@ -60,6 +60,7 @@ namespace PrivaPub.Models.Post
 		public string ActorURI { get; set; }//attributedTo
 		public string Url { get; set; }
 		public string ContextURI { get; set; }
+		public DateTime? LockedAt { get; set; }//no more replies: its community's moderators locked it (Lemmy's Lock, or commentsEnabled false)
 		public string QuoteURI { get; set; }
 		public string QuotedPostId { get; set; }//our copy of the quoted post, once fetched
 		public QuoteState QuoteState { get; set; }