T11: Mastodon 4.7.3 in the pasture

peers/mastodon.sh runs Mastodon's web and sidekiq containers on a shared Postgres and Redis
(peers/shared.sh). They trust Caddy's CA through SSL_CERT_FILE and reach private addresses
through ALLOWED_PRIVATE_ADDRESSES. Its users and tokens come from tootctl and rails runner.

scenarios/mastodon.sh adds 49 checks, as listed in docs/INTEROP.md: follows, posts,
replies, likes and boosts with undos, DMs, polls, FEP-044f quotes both ways, media through
the proxy, edits, deletes, locked follows, a circle request, reports, blocks and statistics.
Two are expected failures:
- inbound Block (P7);
- circle posts. Mastodon 4.7 loses the recipient of deliveries to its numeric
  /ap/users/<id>/inbox and then drops a post that names no local account. The fix on our
  side changes what a circle reveals, so it waits for the owner.

GoToSocial and Mastodon together: 86 passed, 0 failed.

The pasture now copies Caddy's root certificate reliably, readable by the peers, and
rebuilds the bundle each time. The CA directory is mounted shared (:z), because a private
:Z label locks out every container but the last. pfetch reaches PrivaPub's own https URIs
through Caddy. PRIVAPUB_ENV passes settings to PrivaPub, which scenarios/crawler.sh uses to
check the opt-in crawler against Mastodon: it visits, describes and reads the peers list.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01ELjqpznMFMNrJoJUj6K5p2

tools/pasture/Caddyfile

@@ -12,3 +12,8 @@ gts.test {
 	tls internal
 	reverse_proxy pasture-gts:80
 }
+
+mastodon.test {
+	tls internal
+	reverse_proxy pasture-mastodon:3000
+}