Closing the dialog returned focus to the old pane, and that focus-in
counted as a newer navigation, so the card's focus_pane was dropped.
The board now reports the chosen pane from its closed handler and the
app focuses it on idle. The display test answers pane.get and asserts
the pane actually changes.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>