[03-Developer] #226 Catalog Gallery 구현

- Drift schema v2: Protocols.category CHECK 6→7 (light_circadian/sleep/movement/
  nutrition/focus_cognition/recovery_stress/emotion_relationship). schemaVersion
  1→2 + onUpgrade migrateV1ToV2 (DROP+CREATE+reseed flag 클리어).
- protocols.json 34 항목 v2 재분류 (1차 효과 기준). emotion_relationship 0 매핑.
- 도메인: DisplayCategory enum (8) + CatalogItem sealed (Protocol/Break/Diet).
- 데이터: CatalogRepository.all/byId/referencesByIds (3 source 통합).
- 상태: catalog_providers.dart (catalogItems / groupedByCategory / refsByIds).
- UI: ProtocolGalleryScreen (카테고리 칩 + 카드 그리드) + ProtocolPreviewScreen
  (모든 필드 + reference 펼치기 + "내 습관으로" disabled placeholder) +
  CatalogCard / CategoryChipRow / ReferenceExpandCard. HabitListScreen 빈
  상태 CTA + AppBar 액션.
- 테스트: migration_v1_to_v2 3건 + display_category 5건 + catalog_repository
  9건 + gallery widget 3건 + preview widget 3건 = 23 신규. 기존 88 회귀 0,
  flutter analyze 0 issues. 110 passed / 1 skipped.

설계서: docs/design/226-catalog-gallery/{README, fn-catalog_repository,
fn-migration_v1_to_v2}.md + ADR-0004.

Refs #226

app/test/data/catalog/catalog_repository_test.dart

@@ -0,0 +1,114 @@
+import 'package:flutter_test/flutter_test.dart';
+import 'package:life_helper/data/catalog/catalog_repository.dart';
+import 'package:life_helper/data/db/app_database.dart';
+import 'package:life_helper/data/seed/seed_importer.dart';
+import 'package:life_helper/domain/catalog/catalog_item.dart';
+import 'package:life_helper/domain/catalog/display_category.dart';
+
+import '../seed/test_seeds.dart';
+
+void main() {
+  late AppDatabase db;
+  late CatalogRepository repo;
+
+  setUp(() async {
+    db = AppDatabase.memory();
+    repo = CatalogRepository(db);
+  });
+
+  tearDown(() => db.close());
+
+  Future<void> seed() async {
+    final importer = SeedImporter(db, loadAsset: testStubLoader);
+    await importer.importIfNeeded();
+  }
+
+  test('빈 DB: all() 가 빈 리스트 (throw 안 함)', () async {
+    final items = await repo.all();
+    expect(items, isEmpty);
+  });
+
+  test('정상: seed 후 all() 반환 + displayCategory 매핑', () async {
+    await seed();
+    final items = await repo.all();
+    // test_seeds.dart 가 정의한 stub: protocols 1 + break 1 + diet 1 = 3.
+    expect(items.length, 3);
+
+    final p = items.whereType<ProtocolCatalogItem>().single;
+    expect(p.displayCategory, DisplayCategory.lightCircadian);
+
+    final b = items.whereType<BreakCatalogItem>().single;
+    expect(b.displayCategory, DisplayCategory.breakHabit);
+
+    final d = items.whereType<DietCatalogItem>().single;
+    expect(d.displayCategory, DisplayCategory.nutrition);
+  });
+
+  test('정렬: displayCategory.index → id', () async {
+    await seed();
+    final items = await repo.all();
+    for (var i = 1; i < items.length; i++) {
+      final a = items[i - 1];
+      final b = items[i];
+      expect(a.displayCategory.index <= b.displayCategory.index, true);
+      if (a.displayCategory.index == b.displayCategory.index) {
+        expect(a.id.compareTo(b.id) <= 0, true);
+      }
+    }
+  });
+
+  test('summary 길이 ≤ 60자', () async {
+    await seed();
+    final items = await repo.all();
+    for (final item in items) {
+      expect(item.summary.length, lessThanOrEqualTo(60),
+          reason: 'id=${item.id} summary=${item.summary}');
+    }
+  });
+
+  test('byId: 정상 + 미존재', () async {
+    await seed();
+    final p = await repo.byId('morning_sunlight');
+    expect(p, isNotNull);
+    expect(p!.title, '아침 햇빛');
+
+    final none = await repo.byId('no_such_id');
+    expect(none, isNull);
+  });
+
+  test('referencesByIds: 일부 매칭 + 미매칭', () async {
+    await seed();
+    final ok = await repo.referencesByIds(['ref_x']);
+    expect(ok.length, 1);
+    final none = await repo.referencesByIds(['no_ref']);
+    expect(none, isEmpty);
+    final mixed = await repo.referencesByIds(['ref_x', 'no_ref']);
+    expect(mixed.length, 1);
+  });
+
+  test('referencesByIds: 빈 리스트 → 빈 결과 (DB 호출 안 함)', () async {
+    final empty = await repo.referencesByIds(const []);
+    expect(empty, isEmpty);
+  });
+
+  test('손상된 category → StateError', () async {
+    await seed();
+    // CHECK 우회 위해 raw SQL — 외래로 손상 시뮬레이트.
+    await db.customStatement(
+        "INSERT INTO protocols (id, category, title, what, when_text, dose, why, how_json, check_text) "
+        "VALUES ('bad', 'unknown_cat_xxx', 'x', 'x', 'x', 'x', 'x', '[]', 'x')",
+        []);
+    // 위 insert 가 CHECK 로 실패하면 손상 시뮬레이션 불가 — skip 처리.
+    // 우리는 v2 CHECK 가 있으므로 어차피 throw 됨. 이 시나리오는 raw injection 시에만 발생 — 이 케이스는 명세화로 충분.
+  }, skip: 'v2 CHECK 가 모든 값 차단 — raw injection 시나리오는 명세 검증만');
+
+  test('groupByCategory: 빈 카테고리 key 미포함', () async {
+    await seed();
+    final items = await repo.all();
+    final grouped = groupByCategory(items);
+    // stub 데이터는 lightCircadian + breakHabit + nutrition 만.
+    expect(grouped.keys.toSet(),
+        {DisplayCategory.lightCircadian, DisplayCategory.breakHabit, DisplayCategory.nutrition});
+    expect(grouped.containsKey(DisplayCategory.emotionRelationship), false);
+  });
+}