fix(composer): keep model rows on one line and truncate long names - #1717

The model menu wrapped a long model name onto a second line, so a row's
height varied with its name and the list read unevenly. The name now takes
whatever width the row has left after its trailing markers and truncates
with an ellipsis beyond that.

The provider trailing each recent row also yields width before the model
name, so a long name is not the only part that has to survive on the shared
line. The full name and the wire id stay available as the row's title.