#16038 feat(catalog): add GET /v1/catalogs/{id}

We want a dashboard page for each catalog version, showing what was in it (#16039). There was no way to fetch a single version and its products, so this adds one.

• GET /v1/catalogs/{id} (private) returns the catalog, its products, and the IDs of the versions before and after it.
• Regenerated the TypeScript client.