TEST: 同步复述评分开关测试文案为「Show rating during retelling」

commit 49bd38a 改了开关文案后测试仍按旧文案查找 widget，导致 4 个用例失败。更新 3 处 predicate，开关 value 语义未变。

Author: echo-loop

test/screens/learning_settings_screen_test.dart

@@ -79,7 +79,7 @@ void main() {
       (w) =>
           w is SwitchListTile &&
           w.title is Text &&
-          (w.title as Text).data == 'Disable rating during retelling',
+          (w.title as Text).data == 'Show rating during retelling',
     );
     final ratingTile = tester.widget<SwitchListTile>(ratingFinder);
     expect(ratingTile.value, isTrue);
@@ -144,7 +144,7 @@ void main() {
       (w) =>
           w is SwitchListTile &&
           w.title is Text &&
-          (w.title as Text).data == 'Disable rating during retelling',
+          (w.title as Text).data == 'Show rating during retelling',
     );
     await tester.tap(ratingFinder);
     await tester.pumpAndSettle();
@@ -185,7 +185,7 @@ void main() {
       (w) =>
           w is SwitchListTile &&
           w.title is Text &&
-          (w.title as Text).data == 'Disable rating during retelling',
+          (w.title as Text).data == 'Show rating during retelling',
     );
     final ratingTile = tester.widget<SwitchListTile>(ratingFinder);
     expect(ratingTile.value, isTrue);
@@ -199,7 +199,7 @@ void main() {
       (w) =>
           w is SwitchListTile &&
           w.title is Text &&
-          (w.title as Text).data == 'Disable rating during retelling',
+          (w.title as Text).data == 'Show rating during retelling',
     );
     final ratingTile = tester.widget<SwitchListTile>(ratingFinder);
     expect(ratingTile.value, isFalse);