Add other VPAT catalogs to catalog/data directory and update librarian to generate combined ones

- [ ] Add other VPAT catalogs to catalog/data directory.
- [x] Update librarian to generate combined ones.
- [x] Added better error handling/test coverage.

Start by inspecting the catalog/data directory and the librarian entry point to determine which VPAT catalogs are already present and how combined catalogs are generated. The issue does not name the additional catalogs, so confirm the intended sources before adding them; done means the catalogs are present and combined generation remains covered by the existing tests.

Written by the indexing model from the issue text.