test(app): cover routing and secure socks migrations

Cover legacy Auto and ASS preference migration, authenticated SOCKS session generation and the stock-runtime Xray SOCKS schema so future runtime changes cannot silently restore the old fixed-port/no-auth behavior.

test/auto_to_tun_migration_test.dart

@@ -0,0 +1,20 @@
+import 'package:flutter_test/flutter_test.dart';
+import 'package:shared_preferences/shared_preferences.dart';
+import 'package:revoltvpn/logic/connection_settings.dart';
+
+void main() {
+  TestWidgetsFlutterBinding.ensureInitialized();
+
+  test('legacy Auto connection mode migrates to TUN', () async {
+    SharedPreferences.setMockInitialValues(<String, Object>{
+      'connection_mode': 'auto',
+      'app_routing_mode': 'all',
+    });
+
+    await ConnectionSettings.initialize();
+
+    expect(ConnectionSettings.mode, ConnectionMode.tun);
+    final prefs = await SharedPreferences.getInstance();
+    expect(prefs.getString('connection_mode'), ConnectionMode.tun.name);
+  });
+}