feat: app 骨架 + 网络层 + 认证（登录/注册）

- flutter create 初始化 + 依赖（riverpod 3/dio/go_router/three_dart 0.0.16）
- ApiClient：JWT 拦截器 + 统一响应解包 + 401 登出回调 + multipart 上传
- TokenStorage（shared_preferences）+ AuthNotifier 登录/登出
- 登录页（含注册对话框）+ 4 Tab 主框架
- 6 个单元测试通过（网络层 4 + 认证 2）

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

test/core/auth/auth_provider_test.dart

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+import 'package:dio/dio.dart';
+import 'package:flutter_riverpod/flutter_riverpod.dart';
+import 'package:flutter_test/flutter_test.dart';
+import 'package:slogan_app/core/auth/auth_provider.dart';
+import 'package:slogan_app/core/network/api_client.dart';
+import 'package:slogan_app/core/storage/token_storage.dart';
+
+import '../network/api_client_test.dart';
+
+void main() {
+  test('登录成功：token 持久化 + 状态 authenticated', () async {
+    final adapter = MockAdapter();
+    adapter.onRequest = (o) => Response(
+        requestOptions: o,
+        data: {
+          'code': 0,
+          'message': 'OK',
+          'data': {
+            'token': 'jwt-token',
+            'user': {'id': 7, 'name': '测试'}
+          }
+        });
+    final storage = InMemoryTokenStorage();
+    final container = ProviderContainer(overrides: [
+      tokenStorageProvider.overrideWithValue(storage),
+      apiClientProvider.overrideWith((ref) => ApiClient(
+          tokenStorage: storage,
+          dio: Dio(BaseOptions(baseUrl: 'http://test'))
+            ..httpClientAdapter = adapter)),
+    ]);
+    addTearDown(container.dispose);
+
+    await container.read(authProvider.notifier).login('a', '123456');
+    final state = container.read(authProvider);
+    expect(state.value?.authenticated, true);
+    expect(state.value?.userId, 7);
+    expect(storage.token, 'jwt-token');
+  });
+
+  test('登录失败：状态 error 携带 message', () async {
+    final adapter = MockAdapter();
+    adapter.onRequest = (o) => Response(
+        requestOptions: o,
+        data: {'code': 50, 'message': '账号不存在', 'data': null});
+    final storage = InMemoryTokenStorage();
+    final container = ProviderContainer(overrides: [
+      tokenStorageProvider.overrideWithValue(storage),
+      apiClientProvider.overrideWith((ref) => ApiClient(
+          tokenStorage: storage,
+          dio: Dio(BaseOptions(baseUrl: 'http://test'))
+            ..httpClientAdapter = adapter)),
+    ]);
+    addTearDown(container.dispose);
+
+    await container.read(authProvider.notifier).login('a', '123456');
+    final state = container.read(authProvider);
+    expect(state.hasError, true);
+    expect(state.error.toString(), contains('账号不存在'));
+    expect(state.value?.authenticated, false);
+  });
+}
+
+/// 内存版 TokenStorage（测试用，无需 SharedPreferences 插件）
+class InMemoryTokenStorage extends TokenStorage {
+  String? _t;
+
+  @override
+  String? get token => _t;
+
+  @override
+  Future<void> load() async {}
+
+  @override
+  Future<void> save(String token) async => _t = token;
+
+  @override
+  Future<void> clear() async => _t = null;
+}

test/core/network/api_client_test.dart

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+import 'dart:convert';
+import 'dart:typed_data';
+
+import 'package:dio/dio.dart';
+import 'package:flutter_test/flutter_test.dart';
+import 'package:slogan_app/core/network/api_client.dart';
+import 'package:slogan_app/core/network/api_exception.dart';
+import 'package:slogan_app/core/storage/token_storage.dart';
+
+/// 可编程 mock 的 Dio adapter
+class MockAdapter implements HttpClientAdapter {
+  Response Function(RequestOptions options)? onRequest;
+
+  @override
+  Future<ResponseBody> fetch(RequestOptions options,
+      Stream<Uint8List>? requestStream, Future<void>? cancelFuture) async {
+    final r = onRequest?.call(options);
+    if (r == null) return ResponseBody.fromString('', 500);
+    return ResponseBody.fromString(
+        jsonEncode(r.data), r.statusCode ?? 200,
+        headers: {
+          Headers.contentTypeHeader: [Headers.jsonContentType]
+        });
+  }
+
+  @override
+  void close({bool force = false}) {}
+}
+
+class _FakeTokenStorage extends TokenStorage {
+  String? _t;
+
+  _FakeTokenStorage(this._t);
+
+  @override
+  String? get token => _t;
+
+  @override
+  Future<void> load() async {}
+
+  @override
+  Future<void> save(String token) async => _t = token;
+
+  @override
+  Future<void> clear() async => _t = null;
+}
+
+void main() {
+  late MockAdapter adapter;
+  late ApiClient client;
+
+  setUp(() {
+    adapter = MockAdapter();
+    client = ApiClient(
+        tokenStorage: _FakeTokenStorage('test-token'),
+        dio: Dio(BaseOptions(baseUrl: 'http://test'))..httpClientAdapter = adapter);
+  });
+
+  test('成功响应解析 data', () async {
+    adapter.onRequest = (o) => Response(
+        requestOptions: o,
+        data: {'code': 0, 'message': 'OK', 'data': {'id': 1}});
+    final id = await client.post<Map<String, dynamic>>('/x', {});
+    expect(id['id'], 1);
+  });
+
+  test('code != 0 抛 ApiException 带 message', () async {
+    adapter.onRequest = (o) => Response(
+        requestOptions: o,
+        data: {'code': 50, 'message': '衣橱服装不足', 'data': null});
+    expect(
+      () => client.get<Map<String, dynamic>>('/x'),
+      throwsA(isA<ApiException>()
+          .having((e) => e.code, 'code', 50)
+          .having((e) => e.message, 'message', '衣橱服装不足')),
+    );
+  });
+
+  test('请求携带 Bearer token', () async {
+    String? auth;
+    adapter.onRequest = (o) {
+      auth = o.headers['Authorization'];
+      return Response(
+          requestOptions: o, data: {'code': 0, 'message': 'OK', 'data': null});
+    };
+    await client.get<dynamic>('/x');
+    expect(auth, 'Bearer test-token');
+  });
+
+  test('401 触发登出回调', () async {
+    var called = false;
+    client.onUnauthorized = () => called = true;
+    adapter.onRequest = (o) => Response(
+        requestOptions: o,
+        statusCode: 401,
+        data: {'code': 401, 'message': '未登录', 'data': null});
+    try {
+      await client.get<dynamic>('/x');
+    } catch (_) {}
+    expect(called, true);
+  });
+}