Improve performance for clearing history.

lib/foundation/history.dart

@@ -307,6 +307,8 @@ class HistoryManager with ChangeNotifier {
   }
 
 void clearUnfavoritedHistory() {
+  _db.execute('BEGIN TRANSACTION;');
+  try {
     final idAndTypes = _db.select("""
       select id, type from history;
     """);
@@ -320,6 +322,11 @@ class HistoryManager with ChangeNotifier {
         """, [id, type.value]);
       }
     }
+    _db.execute('COMMIT;');
+  } catch (e) {
+    _db.execute('ROLLBACK;');
+    rethrow;
+  }
   updateCache();
   notifyListeners();
 }

lib/pages/history_page.dart

@@ -147,6 +147,7 @@ class _HistoryPageState extends State<HistoryPage> {
                   },
                   child: Text('Clear Unfavorited'.tl),
                 ),
+                const SizedBox(width: 4),
                 Button.filled(
                   color: context.colorScheme.error,
                   onPressed: () {