MHR - Separate the Make and Model values from the legacy registration records

- In the legacy system, the "Make" and "Model" were stored as a single text field. This legacy data now needs to be separated into two distinct fields: "Make" and "Model."

The issue does not name files, tests, or an entry point. Start by locating the legacy registration data model and its database migration or import path, then trace where the combined Make and Model value is read and stored. Done means legacy records have distinct Make and Model values, with the relevant migration or data-handling tests passing.

Written by the indexing model from the issue text.