next method
Navigate to next entry (newer). Returns null if past the end (back to current input).
Implementation
String? next() {
if (_currentIndex < 0) return null; // Not navigating.
if (_currentIndex < _entries.length - 1) {
_currentIndex++;
return _entries[_currentIndex];
} else {
// Past the end — restore saved input.
_resetNavigation();
return _savedInput;
}
}