fix multiple setting pages and search pages

lib/foundation/favorites.dart

@@ -167,6 +167,13 @@ class LocalFavoritesManager with ChangeNotifier {
         order_value int
       );
     """);
+    _db.execute("""
+      create table if not exists folder_sync (
+        folder_name text primary key,
+        source_key text,
+        source_folder text
+      );
+    """);
   }
 
   List<String> find(String id, ComicType type) {

lib/pages/main_page.dart

@@ -89,14 +89,14 @@ class _MainPageState extends State<MainPage> {
             icon: Icons.search,
             label: "Search".tl,
             onTap: () {
-              to(() => const SearchPage());
+              to(() => const SearchPage(), preventDuplicate: true);
             },
           ),
         PaneActionEntry(
           icon: Icons.settings,
           label: "Settings".tl,
           onTap: () {
-            to(() => const SettingsPage());
+            to(() => const SettingsPage(), preventDuplicate: true);
           },
         )
       ],