P7: FEP-268d searchableBy decides what search finds

A remote account's searchableBy, and a post's own, outrank indexable in status search: Public lets anyone find a
public post, the author's followers only those who follow it, anything else nobody but those it already reaches
(their own, named, favourited, bookmarked or boosted posts). Read on actors and posts, kept through edits; PrivaPub
does not emit it.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_012CzABvBkbcFqoHdmi8b9WB

docs/ROADMAP.md

@@ -712,7 +712,9 @@ it, raw where it doesn't.
   - FEP-8fcf followers sync: **done 2026-10-06** (owner decision; sent: the digest of a persona's followers on the
     receiving server, and a signed roll-call listing only them; honoured: a sender's digest of its followers here,
     mended from its list; checked live against Mastodon, all four ways a follow can be lost);
-  - `indexable`/`discoverable`/`searchableBy`;
+  - `indexable`/`discoverable`/`searchableBy`: **done 2026-10-07** (account search already left out undiscoverable
+    accounts; status search now reads FEP-268d `searchableBy` on remote accounts and on each post, which outranks
+    `indexable`: Public, the author's followers (the reader must follow), or nobody else; not emitted by us);
   - edit history from `formerRepresentations`: **done 2026-10-06** (Pleroma's and Akkoma's earlier versions, for a post
     met after its edits and for the edits missed in between);
   - PeerTube reply rules and `ApproveReply`: **done 2026-10-06** (FEP-5624's `canReply`: a reply waits for the author's