Replies a post's author approves (FEP-5624), checked live with PeerTube

PeerTube puts canReply on a video whose comments wait for approval, and answers each comment with ApproveReply. A
persona's reply to such a post now waits (privapub.approval: pending), its Create going to the author alone; the
author's ApproveReply, signed by the author and naming the post answered, lets it out to its audience with
replyApproval, and RejectReply leaves it ours. A null canReply (PeerTube's open comments) says nothing; an empty one
refuses. The PeerTube scenario holds a comment for review and approves it through PeerTube's API (28 checks).

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

PrivaPub/Federation/Inbox/Handlers/ReplyApprovalHandler.cs

@@ -0,0 +1,35 @@
+using PrivaPub.Domain.Statuses;
+using PrivaPub.Models.User;
+
+using System.Text.Json.Nodes;
+
+namespace PrivaPub.Federation.Inbox.Handlers
+{
+	// FEP-5624 (PeerTube): the author of a post whose canReply asks it to approve each reply lets one of ours in, which then
+	// goes to its audience carrying the approval (replyApproval)
+	public class ReplyApprovalHandler : IActivityHandler
+	{
+		readonly IInteractionApprovals _approvals;
+
+		public ReplyApprovalHandler(IInteractionApprovals approvals) => _approvals = approvals;
+
+		public virtual string Type => "ApproveReply";
+
+		protected virtual bool Approves => true;
+
+		public async Task Handle(JsonNode activity, ForeignAvatar actor, CancellationToken token) =>
+			await _approvals.Answered(activity, actor, Approves, token);
+	}
+
+	// and refuses one, which stays ours alone
+	public class ReplyRejectionHandler : ReplyApprovalHandler
+	{
+		public ReplyRejectionHandler(IInteractionApprovals approvals) : base(approvals)
+		{
+		}
+
+		public override string Type => "RejectReply";
+
+		protected override bool Approves => false;
+	}
+}