Votes a community relays count

Lemmy, PieFed and Mbin relay their members' votes, and the undoing of
them, inside the community's Announce; PrivaPub dropped them all as
unsupported (G-0003, the Lemmy scenario's expected failures). A relayed
Like, Dislike or Undo from a community a persona follows is now handled
as if its actor had sent it. The community vouches for what accounts on
its own server do and for what is done to its own posts, as Lemmy trusts
it (refetching every vote would not scale); a vote from elsewhere on
anything else is believed only once fetched from its own origin.
Moderation relayed the same way is still open.

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

PrivaPub.Tests/Support/Harness.cs

@@ -70,6 +70,7 @@ namespace PrivaPub.Tests.Support
 				new FlagHandler(Db, Local),
 				new BlockHandler(Db, Local)
 			};
+			((AnnounceHandler)Handlers.First(h => h is AnnounceHandler)).Relays = Handlers;
 			Processor = new InboxProcessor(Remote, Handlers, NullLogger<InboxProcessor>.Instance, Ledger);
 			Follows = new FollowService(Db, Local, Remote, Delivery, new KeyLocalizer<GenericRes>(), NullLogger<FollowService>.Instance);
 			Content = new ContentRenderer(Local, Remote);