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

CLAUDE.md

@@ -559,6 +559,8 @@ tools/pasture/run.sh down                                            # removes e
   `connection`) and its API is v3 (`/api/v3`, `sort=New`, `resolve_object` answering views). It takes private messages
   only as `ChatMessage`, which PrivaPub sends it, a first message too (invariant 17). `scenarios/lemmy19.sh`, 30
   checks.
+- **Pins (`scenarios/pins.sh`, needs mastodon):** a Mastodon account pins and unpins while alice follows it, alice pins
+  and unpins while it follows her, and a fresh account's earlier pin shows once PrivaPub resolves it. 8 checks.
 - **Smithereen (1.0.3):** its image on the shared MySQL (database `smithereen`, its schema from the image's commit),
   with imgproxy and a file server behind Caddy as `smithereen.test` (`/i` and `/s`), trusting the CA through a JDK
   store with it added (`JAVA_TOOL_OPTIONS`). MySQL takes its stored functions only with