Previously pressing Escape in any setup wizard menu called sys.exit(1),
killing the entire wizard with no way to recover. Now:
- prompt_choice: Escape keeps the current default and moves on (prints
'Skipped (keeping current)'). Shows '↑/↓ Navigate Enter Select
Esc Skip Ctrl+C Exit' hint.
- prompt_checklist: Escape returns pre-selected items instead of empty
list. Shows 'SPACE Toggle ENTER Confirm ESC Skip Ctrl+C Exit'.
- prompt_yes_no: now catches KeyboardInterrupt/EOFError properly.
- Fallback number prompts also show control hints.
Ctrl+C still exits the wizard cleanly.