refactor: rename catalog module to datastore

[giogam]

The catalog/ top-level directory was named after the Catalog service - one concrete backend implementation of the DataStore interface. These changesets and operations work against the abstract cldfdatastore.DataStore interface and are backend-agnostic (other backends exist, e.g. file-based).

• Move all changesets and operations to datastore/changesets and datastore/operations
• Rename operation IDs from catalog-* to datastore-* (display-only; runtime identity uses UUIDs)
• Update all "Catalog service" references in comments and log messages to "Datastore"
• Fix filename typo: detele_address_ref_test.go -> delete_address_ref_test.go
• Replace catalog/ source files with backward-compat type-alias shims pointing to datastore/

Existing consumers importing catalog/changesets or catalog/operations continue to compile without changes. Update imports to datastore/ when convenient.

[cl-sonarqube-production]

Quality Gate failed

Failed conditions
0.0% Coverage on New Code (required ≥ 75%)

See analysis details on SonarQube

[graham-chainlink]

More a thought, i wonder if our users are educated enough to tell the difference between catalog and datastore? WIll they be confuse if there are both catalog and datastore in this repo?

[giogam]

More a thought, i wonder if our users are educated enough to tell the difference between catalog and datastore? WIll they be confuse if there are both catalog and datastore in this repo?

Good question. We’ve already spent quite a bit of time explaining that, though there’s probably still some confusion around it.

From a user’s perspective, they always interact with the DataStore API, regardless of whether the underlying implementation is file-based or catalog-backed. Because of that, I think this repo should consistently refer to it as datastore and avoid mentioning catalog directly.