fix(study): cramming again after turning front and back

A session begun anew (turned to the other side, its settings changed, or
tried again) kept the cards it had crammed before, so a cram of a few
cards turned round said at once there was nothing to study. It now
crams every card again.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Signed-off-by: Tizian 「ティツィアーン」 <raisondetredev@pm.me>

halkyon_learn_flutter/lib/src/feature/study/bloc/study_session_bloc.dart

@@ -183,6 +183,9 @@ class StudySessionBloc(
     _learnAnyway = false;
     _given.clear();
     _done.clear();
+    // Cramming begins again with every card: turned to the other side, or
+    // with other settings, those crammed before are new to this session.
+    _crammed.clear();
     return _startRound(emit);
   }
 

halkyon_learn_flutter/test/feature/study/bloc/study_session_bloc_test.dart

@@ -912,6 +912,33 @@ void main() {
       });
     });
 
+    test('turning front and back crams every card again, the other way '
+        'round (it said there was nothing to study)', () async {
+      await cards.create('japanese', card('猫'));
+      await cards.create('japanese', card('犬'));
+      await study(const StudyOptions(mode: LearnMode.cram));
+
+      await withClock(Clock(() => now), () async {
+        final bloc = session();
+        addTearDown(bloc.close);
+        expect((await showing(bloc, '猫')).asksBack, isFalse);
+
+        bloc.add(const StudySessionEventBackFirstToggled());
+
+        final turned = await until(
+          bloc,
+          (s) =>
+              (s is StudySessionStateShowing && s.asksBack) ||
+              s is StudySessionStateNothing,
+        );
+        expect(turned, isA<StudySessionStateShowing>());
+        expect(
+          (turned as StudySessionStateShowing).card.content.front,
+          text('猫'),
+        );
+      });
+    });
+
     test('newest first takes the studyset backwards', () async {
       await cards.create('japanese', card('猫'));
       await cards.create('japanese', card('犬'));