Add automatic synchronization scheduler that allows users to configure
periodic sync intervals for LoTW and DCL via the settings page.
Features:
- Users can enable/disable auto-sync per service (LoTW/DCL)
- Configurable sync intervals (1-720 hours)
- Settings page UI for managing auto-sync preferences
- Dashboard shows upcoming scheduled auto-sync jobs
- Scheduler runs every minute, triggers syncs when due
- Survives server restarts via database persistence
- Graceful shutdown support (SIGINT/SIGTERM)
Backend:
- New autoSyncSettings table with user preferences
- auto-sync.service.js for CRUD operations and scheduling logic
- scheduler.service.js for periodic tick processing
- API endpoints: GET/PUT /auto-sync/settings, GET /auto-sync/scheduler/status
Frontend:
- Auto-sync settings section in settings page
- Upcoming auto-sync section on dashboard with scheduled job cards
- Purple-themed UI for scheduled jobs with countdown animation
Co-Authored-By: Claude <noreply@anthropic.com>
