getReviewIntroSeen method
One-time flag for the spaced-repetition intro banner shown at the top
of ReviewSessionScreen. The banner replaces the standalone
/onboarding/review screen — the explanation only surfaces when the
user actually lands in the review flow and goes away forever after
they dismiss it.
Implementation
Future<bool> getReviewIntroSeen() async {
final p = await _prefs();
return p.getBool(_reviewIntroSeenKey) ?? false;
}