fix(tasks): guard loop name length and surface loop ownership in the UI

Review follow-up:

- Reject loop files whose frontmatter name exceeds MAX_TASK_NAME_LENGTH
  (80): task names are clamped at storage time, so a raw name longer than
  the limit could never match the stored task identity. The file is treated
  as malformed (definition: null) instead of creating an unreachable
  definition; MAX_TASK_NAME_LENGTH is now exported from project-config.js
  and shared with loops.js.
- Surface loop-sourced tasks in the scheduled-tasks dialog: tasks carrying
  loopFile show a 'Managed by loop file <path>' note, and the enable
  toggle / edit / delete actions are disabled with an explanatory tooltip,
  since the file remains authoritative and would revert any such change.
  run-now stays available. New locale keys added to all 11 message files
  (i18n parity test enforces exact key sets).
- ScheduledTask type gains an optional loopFile field (additive, unknown
  to older clients).

packages/ui/src/lib/i18n/messages/fr.ts

@@ -105,6 +105,9 @@ export const dict = {
   'sessions.scheduledTasks.dialog.taskToggle.pauseAria': 'Pause {taskName}',
   'sessions.scheduledTasks.dialog.taskToggle.enabled': 'Activé',
   'sessions.scheduledTasks.dialog.taskToggle.paused': 'En pause',
+  'sessions.scheduledTasks.dialog.loopFile.note': 'Gérée par le fichier de boucle {file}',
+  'sessions.scheduledTasks.dialog.loopFile.toggleDisabled': "L'activation est contrôlée par le fichier de boucle ; définissez enabled dans le frontmatter Markdown",
+  'sessions.scheduledTasks.dialog.loopFile.actionsDisabled': 'Les tâches de boucle sont configurées dans leur fichier Markdown .agents/loops',
   'sessions.scheduledTasks.editor.title.edit': 'Modifier une tâche planifiée',
   'sessions.scheduledTasks.editor.title.new': 'Nouvelle tâche planifiée',
   'sessions.scheduledTasks.editor.description': 'Configurez une tâche côté serveur qui crée une nouvelle session et envoie un prompt.',