Add proxy routing and sing-box support

packages/flutter_singbox_proxy/test/flutter_singbox_proxy_test.dart

@@ -0,0 +1,25 @@
+import 'package:flutter_test/flutter_test.dart';
+import 'package:flutter_singbox_proxy/flutter_singbox_proxy.dart';
+
+void main() {
+  test('profile model keeps generic sing-box config boundary', () {
+    final profile = SingboxProxyProfile(
+      id: 'wg-home',
+      name: 'WireGuard Home',
+      type: SingboxProxyProfileType.wireguard,
+      configJson: '{"server":"example.test"}',
+      secretJson: '{"private_key":"secret"}',
+    );
+
+    expect(profile.id, 'wg-home');
+    expect(profile.type, SingboxProxyProfileType.wireguard);
+    expect(profile.secretJson, contains('private_key'));
+  });
+
+  test('runtime options default to blocking unmatched traffic', () {
+    final options = SingboxProxyRuntimeOptions();
+
+    expect(options.preferredBasePort, isNull);
+    expect(options.blockUnmatchedTraffic, isTrue);
+  });
+}