feat(meditate,deploy): Meditate beside the instance, and every server's public address from .env

Meditate's deploy step (ADR 0038, step 7; ADR 0039, D14), as Todo's: the
server's Dockerfile with the library's check compiled beside it, its
production config on its own database and role, compose.meditate.yaml as a
member of the register, its site sending /library/* to the web server and
the rest to the API server, the operator's library read-only in a compose
file of its own, and redeploy.sh, backup.sh and the image replay taking it
in.

Every server's public address now comes from .env (Serverpod's
SERVERPOD_API_SERVER_PUBLIC_HOST and _WEB_SERVER_, which win over the
config file): Train, Todo and Meditate from their domains, Learn from
LEARN_PUBLIC_HOST, unset learn.halkyon.eu as before. Without it a server on
halkyon.li would name halkyon.eu in its SimpleLogin callback, profile pages
and privacy page.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Signed-off-by: Tizian 「ティツィアーン」 <raisondetredev@pm.me>

tool/src/images.dart

@@ -11,6 +11,7 @@ const dartImages = [
   'apps/learn/halkyon_learn_curator/Dockerfile',
   'apps/train/halkyon_train_server/Dockerfile',
   'apps/todo/halkyon_todo_server/Dockerfile',
+  'apps/meditate/halkyon_meditate_server/Dockerfile',
 ];
 
 /// One instruction of a Dockerfile's build stage that the replay follows.