Pins across servers, both ways

An account elsewhere that pins or unpins one of its posts (Add or Remove on its `featured`) now shows those pins on its
profile here (`pinned=true`), in its order and its public posts only; a community's announce of a moderator's Add does
the same for the community. The `featured` collection itself is read with the account's counts, at most once a day, so
pins made before PrivaPub ever saw an account show too. Any other target (Smithereen's wall, a community's moderators)
is dropped. A persona's pin and unpin go to the post's audience as Add and Remove on /trophies, as Mastodon sends them.

Checked live against Mastodon (scenarios/pins.sh, 8 checks). The town's checker learnt three peer rules from the
village: Misskey and Sharkey keep a forwarded reply only with its author's LD signature (only Mastodon signs), they
count no renote by a bot, and Mastodon never sees a Lemmy vote on a post in a community. The village of 2026-10-05
checks clean, 2454 of 2454.

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

docs/INTEROP.md

@@ -145,7 +145,7 @@ Priorities, used throughout:
 | Inbound `Move` with Mastodon's checks (`target` re-fetched, its `alsoKnownAs` lists the old account); move each persona's follow, lists, mutes and blocks (done 2026-10-05) | P1 | `Account.moved` |
 | Re-run WebFinger when `preferredUsername` changes; key accounts on the actor id | P2 | `Account.acct` |
 | Inbound `Block`: stop delivering, hide (**done** 2026-10-04) | P2 | `relationship.blocked_by` |
-| `Add`/`Remove` featured (pins, tags) | P2 | `GET /accounts/:id/statuses?pinned=true` |
+| `Add`/`Remove` featured (pins, tags): pins both ways and the collection read daily, done 2026-10-05; featured tags open | P2 | `GET /accounts/:id/statuses?pinned=true` |
 | Remote like and boost totals | P2 | counts |
 | Read the thread's `context` collection to complete a thread (**done** 2026-10-05, `FetchReplies`) | P2 | `/statuses/:id/context` |
 | Publish `context` and a paged `replies` | P2 | — |