- Add backup types and RecallBackup format - Create backup snapshot engine (createBackupSnapshot) - Add IndexedDB storage for local backups - Implement retention policy (max 10, 30-day cleanup) - Add backup validation and restore logic (merge/replace modes) - Add backup restore UI dialog with preview and confirmation - Add unsaved changes guard hook - Integrate backups section in Settings - Add backup endpoint to export-import API
- Add NoteVersion model for storing note snapshots - Add versions API (list, create, get, restore) - Add version history UI dialog in note detail page - Create version snapshot before each note update
