Unclear purpose of collection selection

When you open the search menu for a catalogue, the page shows a form to select one or more collections. Screenshot:


The purpose of this menu is not very clear. I initially assumed this was a search filter, but from the source code, I think it's used to add search results to collections?

Some suggestions:
- Add a clearer label, e.g. "add selected records to collections" instead of "choose collections".
- Hide or disable the controls when the user has not entered query yet.

Inspect the catalogue search menu and the source code that renders the collection-selection form. Reproduce the menu before and after entering a query, then clarify the label and control visibility so their purpose and enabled state are unambiguous.

Written by the indexing model from the issue text.