Persona separation is tested, the API is smoke-checked on deploy, OAuth rows are pruned

- PersonaSeparationTests: two personas of one login follow the same
  account and post; nothing the API maps for one contains the other's id,
  username or the root id.
- tools/smoke/mastodon-api.sh checks what a client meets first (instance
  v1/v2, discovery, app registration, client credentials, an app token
  refused by a user endpoint, the public timeline, revocation) and, given
  a persona token, verify_credentials, home and notifications. deploy.yml
  runs it after every deploy.
- OAuthPruner removes invalid tokens and authorizations older than two
  weeks, every six hours.
- The consent page no longer sets form-action, which browsers apply to the
  redirect back to the client after the form is posted.

CLAUDE.md gains the Mastodon API layout and invariants.

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

.gitea/workflows/deploy.yml

@@ -104,4 +104,5 @@ jobs:
           code=$(curl -s -o /dev/null -w '%{http_code}' -X POST -H 'Content-Type: application/activity+json' \
             --data '{"type":"Follow","actor":"https://example.org/users/x","object":"'"$PUBLIC_URL"'/peasants/privapub"}' "$PUBLIC_URL/human-centipede")
           [ "$code" = "401" ] || { echo "::error::an unsigned inbox POST answered $code"; exit 1; }
+          tools/smoke/mastodon-api.sh "$PUBLIC_URL"
           echo "::notice::serving $served"