Implement Storage using object_store

### Is your feature request related to a problem or challenge?

We want to offer a Storage implementation backed by `object_store`

### Describe the solution you'd like

_No response_

### Willingness to contribute

None

The issue names a Storage implementation backed by object_store, but no files, tests, or entry points. Start by locating the Storage abstraction and existing backend tests, then determine how object_store fits that interface. Done means the object_store-backed implementation is integrated and covered by appropriate tests.

Written by the indexing model from the issue text.