chore(client): 归档原型阶段新增文件（配置、主题、模型与测试）

为什么：上一批归档只覆盖了「已跟踪文件的修改」，原型阶段新增的文件（app_config、theme、
home_feed/play_ticket 模型、catalog_api、测试目录等）还是未入库状态 —— 而已入库的代码会 import 它们，
留在工作区会导致 HEAD 处的代码编译不过。一并归档，让 HEAD 自洽。

纯归档，无行为改动。

test/engagement/engagement_repository_test.dart

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+import 'dart:convert';
+
+import 'package:flutter_test/flutter_test.dart';
+import 'package:nontonki/core/data/models/engagement_snapshot.dart';
+import 'package:nontonki/core/data/repositories/engagement_repository.dart';
+import 'package:shared_preferences/shared_preferences.dart';
+import 'package:shared_preferences_platform_interface/in_memory_shared_preferences_async.dart';
+import 'package:shared_preferences_platform_interface/shared_preferences_async_platform_interface.dart';
+
+/// Mirrors the private key used by [SharedPreferencesEngagementRepository].
+const _key = 'engagement.v1.demo-local-v1';
+
+void main() {
+  late SharedPreferencesAsync preferences;
+
+  setUp(() {
+    SharedPreferencesAsyncPlatform.instance =
+        InMemorySharedPreferencesAsync.empty();
+    preferences = SharedPreferencesAsync();
+  });
+
+  SharedPreferencesEngagementRepository repository() =>
+      SharedPreferencesEngagementRepository(preferences: preferences);
+
+  Future<EngagementSnapshot> loadRaw(String raw) async {
+    await preferences.setString(_key, raw);
+    return repository().load();
+  }
+
+  test('a first launch reads an empty snapshot', () async {
+    final snapshot = await repository().load();
+
+    expect(snapshot.savedDramaIds, isEmpty);
+    expect(snapshot.likedDramaIds, isEmpty);
+    expect(snapshot.commentsByDrama, isEmpty);
+  });
+
+  test('a snapshot survives a save and reload round trip', () async {
+    await repository().save(
+      const EngagementSnapshot(
+        savedDramaIds: {'signal', 'city'},
+        likedDramaIds: {'city'},
+        commentsByDrama: {
+          'signal': ['first note', 'second note'],
+        },
+      ),
+    );
+
+    final loaded = await repository().load();
+
+    expect(loaded.savedDramaIds, {'signal', 'city'});
+    expect(loaded.likedDramaIds, {'city'});
+    expect(loaded.commentsByDrama, {
+      'signal': ['first note', 'second note'],
+    });
+  });
+
+  test('an empty snapshot round trips as empty collections', () async {
+    await repository().save(const EngagementSnapshot());
+
+    final loaded = await repository().load();
+
+    expect(loaded.savedDramaIds, isEmpty);
+    expect(loaded.likedDramaIds, isEmpty);
+    expect(loaded.commentsByDrama, isEmpty);
+  });
+
+  test('corrupt or non-object payloads fall back to an empty snapshot', () async {
+    for (final raw in <String>[
+      '',
+      'not json at all',
+      '[]',
+      '"a bare string"',
+      '42',
+      'null',
+    ]) {
+      final snapshot = await loadRaw(raw);
+
+      expect(snapshot.savedDramaIds, isEmpty, reason: raw);
+      expect(snapshot.likedDramaIds, isEmpty, reason: raw);
+      expect(snapshot.commentsByDrama, isEmpty, reason: raw);
+    }
+  });
+
+  test('wrongly typed fields are dropped instead of throwing', () async {
+    final snapshot = await loadRaw(
+      jsonEncode({
+        'saved': 'signal',
+        'liked': {'city': true},
+        'comments': {
+          'signal': 'a plain string',
+          'city': ['kept', 7, null, true],
+          'town': <Object>[],
+        },
+      }),
+    );
+
+    expect(snapshot.savedDramaIds, isEmpty);
+    expect(snapshot.likedDramaIds, isEmpty);
+    expect(snapshot.commentsByDrama, {
+      'city': ['kept'],
+      'town': <String>[],
+    });
+  });
+
+  test('a payload missing keys falls back per field', () async {
+    final snapshot = await loadRaw(jsonEncode({'saved': ['signal']}));
+
+    expect(snapshot.savedDramaIds, {'signal'});
+    expect(snapshot.likedDramaIds, isEmpty);
+    expect(snapshot.commentsByDrama, isEmpty);
+  });
+
+  test('save writes only json primitives', () async {
+    await repository().save(
+      const EngagementSnapshot(
+        savedDramaIds: {'signal'},
+        likedDramaIds: {'city'},
+        commentsByDrama: {
+          'signal': ['note'],
+        },
+      ),
+    );
+
+    final raw = await preferences.getString(_key);
+    expect(raw, isNotNull);
+
+    final decoded = jsonDecode(raw!) as Map<String, dynamic>;
+    expect(decoded['saved'], ['signal']);
+    expect(decoded['liked'], ['city']);
+    expect(decoded['comments'], {
+      'signal': ['note'],
+    });
+  });
+}