feat: add Flutter mobile clients and staff delivery API

apps/user_app/test/ui/login_page_test.dart

@@ -0,0 +1,16 @@
+import 'package:flutter/material.dart';
+import 'package:flutter_test/flutter_test.dart';
+import 'package:user_app/app/dependencies.dart';
+import 'package:user_app/data/services/secure_session_store.dart';
+import 'package:user_app/ui/features/auth/login_page.dart';
+
+void main() {
+  testWidgets('login page exposes phone and password fields', (tester) async {
+    final session = UserSession(SecureSessionStore());
+    await tester.pumpWidget(MaterialApp(home: LoginPage(session: session)));
+
+    expect(find.text('瓶安芯'), findsOneWidget);
+    expect(find.byType(TextField), findsNWidgets(2));
+    expect(find.text('安全登录'), findsOneWidget);
+  });
+}