Add TypeScript types for lib

**Feature request**
It would be great to have backup for data.

**Use case**
Many users need this functionality for production deployments.

**Implementation idea**
Add a new config option `enable_backup` with default `false`.

No file, test, or entry point is named. First locate the library configuration handling and determine how backups are expected to work; the issue is complete only when the intended backup behavior and the `enable_backup` option with default `false` are defined and covered.

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