Followers and circle members may like, react, vote and downvote

LikeHandler.MaySee let a remote account interact with a followers-only
post only when the post named it in to, cc or its mentions. Our own
followers-only posts are addressed to the followers collection, never to
each follower, and circle posts were not considered at all, so every
like, reaction, downvote and poll vote from a follower on a
followers-only post, and from a member on a circle post, was dropped as
"not-visible". Likes, dislikes, reactions and poll votes now ask
VisibilityPolicy.RemoteCanSee: anyone for public and unlisted posts, an
addressed account for a DM, an accepted follower or an addressed account
for followers-only, a foreign member for a circle post, and never a
server's instance actor (SignedFetchAuthorizer's alias is for refetches
only).

Found by planning the town's multi-server interaction checks (G-0001).

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

PrivaPub/Domain/Social/Reactions.cs

@@ -1,9 +1,9 @@
 using MongoDB.Driver;
 using MongoDB.Entities;
 
+using PrivaPub.Domain.Privacy;
 using PrivaPub.Federation.Actors;
 using PrivaPub.Federation.Inbox;
-using PrivaPub.Federation.Inbox.Handlers;
 using PrivaPub.Federation.Objects;
 using PrivaPub.Federation.Outbox;
 using PrivaPub.Federation.Rendering;
@@ -43,9 +43,10 @@ namespace PrivaPub.Domain.Social
 
 		public async Task Receive(PostEntity post, ForeignAvatar actor, string content, JsonNode tags, string activityId, CancellationToken token)
 		{
-			if (!LikeHandler.MaySee(post, actor) || Normalise(content, ObjectShapes.Emojis(tags)) is not { } emoji)
+			var visible = await VisibilityPolicy.RemoteCanSee(post, actor, token);
+			if (!visible || Normalise(content, ObjectShapes.Emojis(tags)) is not { } emoji)
 			{
-				Arrival.Drop(LikeHandler.MaySee(post, actor) ? "unparseable" : "not-visible");
+				Arrival.Drop(visible ? "unparseable" : "not-visible");
 				return;
 			}
 			try