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

docs/INTEROP.md

@@ -724,7 +724,10 @@ The account sends `Create{Video}`; the channel (a Group) sends `Announce{Video}`
   - have non-empty `content`, a valid `url` and `published`;
   - have an `id` on the actor's host;
   - have an `inReplyTo` that resolves to the video or one of its comments.
-- `commentsPolicy` 2 rejects replies; 3 holds them until approved.
+- `commentsPolicy` 2 rejects replies; 3 holds them until approved. A video's `canReply` is `null` while comments are
+  open, Public while they wait for approval; PrivaPub reads it as FEP-5624: a persona's comment waits, goes to the video's
+  account alone, and goes out with `replyApproval` once PeerTube's `ApproveReply` arrives (2026-10-06, live: the held
+  comment approved through PeerTube's API reaches PrivaPub as approved).
 - PeerTube signs its fetches.
 - It drops followers that have been unreachable for about 7 days (8.2).