Document 2.10.0: save backups, Minesweeper flag mode, backend 1.5.0
- Home: version 2.10.0+18, backend compatibility 1.5.0, optional backups.
- Getting Started: 2.10.0 artifacts and where backups are stored.
- Games: Minesweeper Flag mode in the bottom bar.
- Features: new Save backups section and account table row.
- Architecture: SaveBackupService, backup storage key, startup hook and
privacy boundary.
- Testing: 245 passing tests and the new save_backup_test.dart.
- Deployment: 2.10.0 image tags and the backend 1.5.0 requirement.
- Troubleshooting: why save backups can be missing or fail.
