initialize method
Implementation
Future<void> initialize() async {
if (_isInitialized) return;
_storage = LittlefishFlutterSecureStorage();
await _storage!.initialize(settings: FlutterSecureStorageSettings.defaults);
// Hydrate active session from disk on startup
await _populateActiveSession();
// Hydrate all known sessions into memory
await _hydrateAllSessions();
_isInitialized = true;
}