fix(learn): Archived and Recently deleted fold during a search

A search opened both sections whatever they were set to, so a tap on
their headers did nothing while one was under way. A search still opens
them, so their matches show, and a tap now folds them until the search
ends, which brings them back as they were left before it.

Whats-New: While searching the library, Archived and Recently deleted fold again when tapped.
Whats-New-De: Beim Suchen in der Bibliothek lassen sich Archiviert und Zuletzt gelöscht wieder einklappen.

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

apps/learn/halkyon_learn_flutter/test/feature/studyset/widget/library_screen_test.dart

@@ -683,6 +683,35 @@ void main() {
     expect(find.text('Kanji'), findsNothing, reason: 'the archive is closed');
   });
 
+  testWidgets('a search opens the archive, which a tap folds for the rest '
+      'of the search', (tester) async {
+    stored(
+      'kanji',
+      'Kanji',
+      secondaryTitle: 'Japanese',
+      archivedAt: DateTime.utc(2026, 10),
+    );
+    await showLibrary(tester);
+
+    await tester.tap(find.byTooltip('Search'));
+    await tester.pumpAndSettle();
+    await tester.enterText(find.byType(TextField), 'kan');
+    await tester.pumpAndSettle();
+    expect(find.text('Kanji'), findsOneWidget);
+
+    await tester.tap(find.text('Archived'));
+    await tester.pumpAndSettle();
+    expect(find.text('Kanji'), findsNothing);
+
+    await tester.enterText(find.byType(TextField), 'kanj');
+    await tester.pumpAndSettle();
+    expect(find.text('Kanji'), findsNothing, reason: 'still folded');
+
+    await tester.tap(find.text('Archived'));
+    await tester.pumpAndSettle();
+    expect(find.text('Kanji'), findsOneWidget);
+  });
+
   testWidgets('a search lists titles starting with what is typed first, then '
       'those holding it as a word, then secondary titles, whatever was changed '
       'last', (tester) async {