NumberInputModel class

Interactive numeric input component.

• Arrow-Up / Ctrl+P → increment by step (clamped to max)
• Arrow-Down / Ctrl+N → decrement by step (clamped to min)
• Digit keys → typed directly (non-digit characters ignored)
• Backspace → delete last character
• Enter → validate and submit
• Escape / Ctrl+C → cancel

The component emits NumberSubmittedMsg on success or NumberCancelledMsg on cancel.

Example:

final model = NumberInputModel(
  prompt: 'Port number:',
  defaultValue: 8080,
  min: 1,
  max: 65535,
  step: 1,
);