alexei.dolgolyov
b0439e39c4
Replace the JSON-based import/export with a proper backup system that copies the SQLite database file directly. Supports manual on-demand backups, periodic scheduled backups via node-cron, configurable retention, file download, and full database restore. - Add backupService with VACUUM INTO for safe DB copies - Add backupScheduler following healthcheckScheduler pattern - Add 6 admin API endpoints (create, list, download, restore, delete, schedule) - Add BackupPanel UI with backup table, confirmation dialogs, schedule config - Add backup fields to SystemSettings schema - Remove old ImportExportPanel, exportService, importService, and related code