What problems was I solving

A previous component reorganisation (ARC-760) copied components/ui/collapsible.tsx into components/collapsibles/collapsible.tsx and repointed the ui/index.ts barrel at the new path. When the only consumer in collapsibles/ was later deleted, the duplicate file was left orphaned and the barrel was still exporting from a soon-to-be-deleted location.

What user-facing changes did I ship

None. This is an internal cleanup with no user-visible behavior change.

How I implemented it

Deleted architect/management-ui/app/main/components/collapsibles/collapsible.tsx and updated architect/management-ui/app/main/components/ui/index.ts to re-export from ./collapsible. I verified there are no remaining imports referencing the removed path and that all live consumers (both direct imports from components/ui/collapsible and indirect imports via the components barrel) resolve to the surviving file.

Description for the changelog

Removed an unused duplicate Collapsible wrapper component from components/collapsibles/ and fixed the components/ui/index.ts barrel export so it re-exports the canonical components/ui/collapsible.tsx. This is a non-user-facing housekeeping change with no runtime impact.