Clickable-refs mandate from Charles: ticket comments link commits,
commit bodies link the Redmine comment URL, Discourse links both —
one click between Redmine/Gitea/Discourse (GLPI/CMDB change control
will extend this). Mechanical body-URL check queued under #441.
scripts/mastodon/post.sh: zero-install curl poster; creds land in
~/.creds/mastodon.env (MASTODON_URL/MASTODON_TOKEN, write scope).
