Refactored DI, serialization, added feedback to document download

lib/features/login/services/authentication_service.dart

@@ -0,0 +1,28 @@
+import 'package:injectable/injectable.dart';
+import 'package:local_auth/local_auth.dart';
+import 'package:paperless_mobile/core/store/local_vault.dart';
+
+@lazySingleton
+class LocalAuthenticationService {
+  final LocalVault localStore;
+  final LocalAuthentication localAuthentication;
+
+  LocalAuthenticationService(
+    this.localStore,
+    this.localAuthentication,
+  );
+
+  Future<bool> authenticateLocalUser(String localizedReason) async {
+    if (await localAuthentication.isDeviceSupported()) {
+      return await localAuthentication.authenticate(
+        localizedReason: localizedReason,
+        options: const AuthenticationOptions(
+          stickyAuth: true,
+          biometricOnly: true,
+          useErrorDialogs: true,
+        ),
+      );
+    }
+    return false;
+  }
+}