Added option to disable background update checking

lib/main.dart

@@ -81,11 +81,15 @@ class MyApp extends StatelessWidget {
       settingsProvider.initializeSettings();
     } else {
       // Register the background update task according to the user's setting
+      if (settingsProvider.updateInterval > 0) {
         Workmanager().registerPeriodicTask('bg-update-check', 'bg-update-check',
             frequency: Duration(minutes: settingsProvider.updateInterval),
             initialDelay: Duration(minutes: settingsProvider.updateInterval),
             constraints: Constraints(networkType: NetworkType.connected),
             existingWorkPolicy: ExistingWorkPolicy.replace);
+      } else {
+        Workmanager().cancelByUniqueName('bg-update-check');
+      }
       bool isFirstRun = settingsProvider.checkAndFlipFirstRun();
       if (isFirstRun) {
         // If this is the first run, ask for notification permissions and add Obtainium to the Apps list

lib/pages/settings.dart

@@ -103,6 +103,10 @@ class _SettingsPageState extends State<SettingsPage> {
                           value: 1440,
                           child: Text('1 Day'),
                         ),
+                        DropdownMenuItem(
+                          value: 0,
+                          child: Text('Never - Manual Only'),
+                        ),
                       ],
                       onChanged: (value) {
                         if (value != null) {

lib/providers/settings_provider.dart

@@ -45,7 +45,7 @@ class SettingsProvider with ChangeNotifier {
   }
 
   set updateInterval(int min) {
-    prefs?.setInt('updateInterval', min < 15 ? 15 : min);
+    prefs?.setInt('updateInterval', (min < 15 && min != 0) ? 15 : min);
     notifyListeners();
   }