- Add GET /api/v1/backup and POST /api/v1/backup/restore endpoints
behind AuthenticatedUser
- Add BackupService to AppState and BackupClient for HTTP access
- Update CLI backup/restore to use API instead of direct DB access
- Remove --database-url flag from backup and restore commands
- Increase body limit to 50MB for restore endpoint
- Add API and CLI tests for auth, export, restore, and round-trip
- Update README to document auth requirement and API endpoints
