Refactor preferences service initialization to lazy load SharedPreferences and make registerDefaultServices synchronous

finlog_app/fluttery/lib/src/preferences/preferences_impl.dart

@@ -2,68 +2,85 @@ import 'package:fluttery/preferences.dart';
 import 'package:shared_preferences/shared_preferences.dart';
 
 class PreferencesImpl implements Preferences {
-  final SharedPreferences _prefs;
+  late final SharedPreferences _prefs;
+  bool _initialized = false;
 
-  /// Constructor
-  PreferencesImpl({required SharedPreferences instance}) : _prefs = instance;
+  Future<void> _ensureInitialized() async {
+    if (!_initialized) {
+      _prefs = await SharedPreferences.getInstance();
+      _initialized = true;
+    }
+  }
 
   @override
   Future<void> setString(String key, String value) async {
+    await _ensureInitialized();
     await _prefs.setString(key, value);
   }
 
   @override
   Future<String?> getString(String key) async {
+    await _ensureInitialized();
     return _prefs.getString(key);
   }
 
   @override
   Future<void> setInt(String key, int value) async {
+    await _ensureInitialized();
     await _prefs.setInt(key, value);
   }
 
   @override
   Future<int?> getInt(String key) async {
+    await _ensureInitialized();
     return _prefs.getInt(key);
   }
 
   @override
   Future<void> setBool(String key, bool value) async {
+    await _ensureInitialized();
     await _prefs.setBool(key, value);
   }
 
   @override
   Future<bool?> getBool(String key) async {
+    await _ensureInitialized();
     return _prefs.getBool(key);
   }
 
   @override
   Future<void> setDouble(String key, double value) async {
+    await _ensureInitialized();
     await _prefs.setDouble(key, value);
   }
 
   @override
   Future<double?> getDouble(String key) async {
+    await _ensureInitialized();
     return _prefs.getDouble(key);
   }
 
   @override
   Future<void> setStringList(String key, List<String> value) async {
+    await _ensureInitialized();
     await _prefs.setStringList(key, value);
   }
 
   @override
   Future<List<String>?> getStringList(String key) async {
+    await _ensureInitialized();
     return _prefs.getStringList(key);
   }
 
   @override
   Future<void> remove(String key) async {
+    await _ensureInitialized();
     await _prefs.remove(key);
   }
 
   @override
   Future<void> clear() async {
+    await _ensureInitialized();
     await _prefs.clear();
   }
-}
+}