Use progressive disclosure and one scroll surface for catalogues

Long configurable catalogues should use category-level progressive disclosure and one scroll surface. Keep category summaries visible with selected and visible counts, expand matching categories during search, preserve categories users opened manually, and avoid fixed-height lists inside an already scrolling dialog.

This applies when the catalogue is moderate enough to remain in the DOM. It does not replace virtualization for thousands of records. Keep search-driven expansion separate from persisted user-open state because delayed native toggle events can follow programmatic changes.