feat: add reading_status_push auto-refresh schedule per library

- Migration 0059: reading_status_push_mode / last / next columns on libraries
- API: update_reading_status_provider accepts push_mode and calculates next_push_at
- job_poller: handles reading_status_push pending jobs
- Indexer scheduler: check_and_schedule_reading_status_push every minute
- Backoffice: schedule select in library settings modal

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

apps/backoffice/lib/i18n/en.ts

@@ -200,6 +200,8 @@ const en: Record<TranslationKey, string> = {
   "libraryActions.sectionReadingStatus": "Reading Status",
   "libraryActions.readingStatusProvider": "Reading Status Provider",
   "libraryActions.readingStatusProviderDesc": "Syncs reading states (read / reading / planned) with an external service",
+  "libraryActions.readingStatusPushSchedule": "Auto-push schedule",
+  "libraryActions.readingStatusPushScheduleDesc": "Automatically push reading progress to the provider on a schedule",
 
   // Reading status modal
   "readingStatus.button": "Reading status",

apps/backoffice/lib/i18n/fr.ts

@@ -198,6 +198,8 @@ const fr = {
   "libraryActions.sectionReadingStatus": "État de lecture",
   "libraryActions.readingStatusProvider": "Provider d'état de lecture",
   "libraryActions.readingStatusProviderDesc": "Synchronise les états de lecture (lu / en cours / planifié) avec un service externe",
+  "libraryActions.readingStatusPushSchedule": "Synchronisation automatique",
+  "libraryActions.readingStatusPushScheduleDesc": "Pousse automatiquement la progression de lecture vers le provider selon un calendrier",
 
   // Reading status modal
   "readingStatus.button": "État de lecture",