A remote account's Block of a persona is enforced

Inbound Block was dropped as an unknown type (the pasture's last
Mastodon expected failure, G-0002). Now, as Mastodon does it: the
follows between the blocker and the persona end here too (nothing is
sent back; the blocker already ended its side), the blocker's posts and
notifications are hidden from the persona and kept out of its home, the
persona's posts are no longer addressed to the blocker by mention or
reply, and the relationship says blocked_by. Undo{Block} lifts it. The
block is kept in BlockedBy, unique per persona and blocker.

The Mastodon scenario checks blocked_by instead of expecting a failure.

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

PrivaPub/Models/Social/Relationships.cs

@@ -10,6 +10,17 @@ namespace PrivaPub.Models.Social
 		public DateTime CreatedAt { get; set; } = DateTime.UtcNow;
 	}
 
+	//a remote account that blocked one of our personas (an inbound Block): its posts and notifications are hidden from the
+	//persona, the follows between them are gone, and the relationship says blocked_by, until it sends Undo{Block}
+	public class BlockedBy : Entity
+	{
+		public string AvatarId { get; set; }
+		public string ActorURI { get; set; }
+		public string AccountId { get; set; }//the blocker's ForeignAvatar.ID
+		public string ActivityURI { get; set; }
+		public DateTime CreatedAt { get; set; } = DateTime.UtcNow;
+	}
+
 	public class Mute : Entity
 	{
 		public string AvatarId { get; set; }