Add simple desktop app

desktop/lib/settings.dart

@@ -0,0 +1,30 @@
+import 'package:musicus_common/musicus_common.dart';
+import 'package:shared_preferences/shared_preferences.dart';
+
+class SettingsStorage extends MusicusSettingsStorage {
+  SharedPreferences _pref;
+
+  Future<void> load() async {
+    _pref = await SharedPreferences.getInstance();
+  }
+
+  @override
+  Future<int> getInt(String key) {
+    return Future.value(_pref.getInt(key));
+  }
+
+  @override
+  Future<String> getString(String key) {
+    return Future.value(_pref.getString(key));
+  }
+
+  @override
+  Future<void> setInt(String key, int value) async {
+    await _pref.setInt(key, value);
+  }
+
+  @override
+  Future<void> setString(String key, String value) async {
+    await _pref.setString(key, value);
+  }
+}