Class ExitBrailleAndSubplotCommand

Command to dismiss braille focus and exit the subplot context in a single action. Used when Escape is pressed while braille mode is active.

The ordering is important for screen reader compatibility:

1. dismissModalScope moves focus to the plot and clears the focus stack,
2. exitSubplot transitions the navigation context to the subplot level,
3. notifyFocusChange defers the UI update (textarea removal) so NVDA/JAWS process the focus change before the braille textarea unmounts.