BIM viewer resizes correctly when layout changes

The viewer no longer stays a fixed width after you toggle split view, close or reopen the sidebar, or switch between one and two versions. It now fills the available space immediately after any of those layout changes. Separately, a version that is still processing now appears with warning styling and a spinning indicator in the version picker — and cannot be selected until processing is complete, preventing a crash that could occur if you tried to switch to it mid-translation.