[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/ui/protocol_preview_screen_test.dart

@@ -0,0 +1,81 @@
+import 'package:flutter/material.dart';
+import 'package:flutter_riverpod/flutter_riverpod.dart';
+import 'package:flutter_test/flutter_test.dart';
+import 'package:life_helper/domain/catalog/catalog_item.dart';
+import 'package:life_helper/domain/catalog/display_category.dart';
+import 'package:life_helper/state/catalog_providers.dart';
+import 'package:life_helper/ui/screens/protocol_preview_screen.dart';
+
+ProtocolCatalogItem _sampleProtocol({List<String> refIds = const []}) =>
+    ProtocolCatalogItem(
+      id: 'morning_sunlight',
+      title: '아침 햇빛',
+      titleEn: 'Morning Sunlight',
+      summary: '기상 후 햇빛',
+      displayCategory: DisplayCategory.lightCircadian,
+      evidenceStrength: 'strong_rct',
+      referenceIds: refIds,
+      what: '기상 후 햇빛 노출.',
+      whenText: '기상 후 30~60분.',
+      dose: '5~10분.',
+      why: 'ipRGC 자극으로 일주기 리셋.',
+      how: const ['밖으로 나간다', '하늘을 쳐다본다'],
+      checkText: '60분 이내 외출',
+      caution: '직사 응시 금지',
+      defaultAnchor: const {'when': '기상 후', 'after_what': '세수'},
+      minDoseForStart: '2분',
+      sourceDoc: 'huberman-protocols.md',
+    );
+
+void main() {
+  Widget buildHarness(CatalogItem item, {List<dynamic> refs = const []}) {
+    return ProviderScope(
+      overrides: [
+        referencesByIdsProvider.overrideWith((ref, ids) async => []),
+      ],
+      child: MaterialApp(home: ProtocolPreviewScreen(item: item)),
+    );
+  }
+
+  testWidgets('Protocol: 모든 핵심 필드 표시', (tester) async {
+    final item = _sampleProtocol();
+    await tester.pumpWidget(buildHarness(item));
+    await tester.pump();
+
+    // Header + 상단 가시 필드.
+    expect(find.text('아침 햇빛'), findsAtLeastNWidgets(1));
+    expect(find.text('Morning Sunlight'), findsOneWidget);
+    expect(find.text('빛/일주기'), findsOneWidget);
+
+    // ListView lazy-builds — 하위 필드는 명시적 스크롤로 가져온다.
+    final scrollable = find.byType(Scrollable).first;
+    for (final t in [
+      'ipRGC 자극으로 일주기 리셋.',
+      '1. 밖으로 나간다',
+      '2. 하늘을 쳐다본다',
+      '60분 이내 외출',
+      '직사 응시 금지',
+      '2분',
+      'huberman-protocols.md',
+    ]) {
+      await tester.scrollUntilVisible(find.text(t), 100,
+          scrollable: scrollable);
+      expect(find.text(t), findsOneWidget, reason: 'missing: $t');
+    }
+  });
+
+  testWidgets('"내 습관으로" 버튼 disabled + tooltip', (tester) async {
+    await tester.pumpWidget(buildHarness(_sampleProtocol()));
+    await tester.pump();
+
+    final button = tester.widget<FilledButton>(find.byType(FilledButton));
+    expect(button.onPressed, isNull);
+    expect(find.byType(Tooltip), findsAtLeastNWidgets(1));
+  });
+
+  testWidgets('reference 없으면 References 섹션 숨김', (tester) async {
+    await tester.pumpWidget(buildHarness(_sampleProtocol(refIds: const [])));
+    await tester.pump();
+    expect(find.textContaining('참고 ('), findsNothing);
+  });
+}