[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/lib/data/catalog/catalog_repository.dart

@@ -0,0 +1,133 @@
+import 'dart:convert';
+
+import '../../domain/catalog/catalog_item.dart';
+import '../../domain/catalog/display_category.dart';
+import '../db/app_database.dart';
+
+/// 3 source (Protocols / BreakProtocols / DietPatterns) → 단일 `List<CatalogItem>`.
+///
+/// 본 이슈 (#226) 의 핵심 변환 한 점. 본 함수는 fn-catalog_repository.md 의 알고리즘대로.
+class CatalogRepository {
+  CatalogRepository(this._db);
+
+  final AppDatabase _db;
+
+  /// 47 항목 (protocols 34 + break 8 + diet 5) 을 displayCategory 기준 정렬해 반환.
+  Future<List<CatalogItem>> all() async {
+    final protocolRows = await _db.select(_db.protocols).get();
+    final breakRows = await _db.select(_db.breakProtocols).get();
+    final dietRows = await _db.select(_db.dietPatterns).get();
+
+    final items = <CatalogItem>[];
+
+    for (final p in protocolRows) {
+      final dc = DisplayCategory.fromProtocolCategory(p.category);
+      if (dc == null) {
+        throw StateError(
+            'unknown protocol category "${p.category}" for id=${p.id}');
+      }
+      items.add(ProtocolCatalogItem(
+        id: p.id,
+        title: p.title,
+        titleEn: p.titleEn,
+        summary: _summary(p.what, fallback: p.title),
+        displayCategory: dc,
+        evidenceStrength: p.evidenceStrength,
+        referenceIds: _decodeIds(p.referenceIdsJson),
+        what: p.what,
+        whenText: p.whenText,
+        dose: p.dose,
+        why: p.why,
+        how: _decodeList(p.howJson),
+        checkText: p.checkText,
+        caution: p.caution,
+        defaultAnchor: _decodeAnchor(p.defaultAnchorJson),
+        minDoseForStart: p.minDoseForStart,
+        sourceDoc: p.sourceDoc,
+      ));
+    }
+
+    for (final b in breakRows) {
+      items.add(BreakCatalogItem(
+        id: b.id,
+        title: b.title,
+        titleEn: null,
+        summary: _summary(b.hubermanSummary, fallback: b.title),
+        evidenceStrength: null,
+        referenceIds: _decodeIds(b.referenceIdsJson),
+        breakCategory: b.category,
+        hubermanSummary: b.hubermanSummary,
+        phases: _decodeList(b.phasesJson),
+        defaultCommonFrames: _decodeList(b.defaultCommonFramesJson),
+        tools: _decodeList(b.toolsJson),
+        medicalWarning: b.medicalWarning,
+      ));
+    }
+
+    for (final d in dietRows) {
+      items.add(DietCatalogItem(
+        id: d.id,
+        title: d.name,
+        titleEn: null,
+        summary: _summary(d.core, fallback: d.name),
+        evidenceStrength: d.evidenceStrength,
+        referenceIds: _decodeIds(d.referenceIdsJson),
+        name: d.name,
+        core: d.core,
+        strengths: _decodeList(d.strengthsJson),
+        weaknesses: _decodeList(d.weaknessesJson),
+        koreanContextFit: d.koreanContextFit,
+        starterLevers: _decodeList(d.starterLeversJson),
+        medicalWarning: d.medicalWarning,
+        linkedProtocolIds: _decodeIds(d.linkedProtocolIdsJson),
+      ));
+    }
+
+    items.sort((a, b) {
+      final c = a.displayCategory.index - b.displayCategory.index;
+      return c != 0 ? c : a.id.compareTo(b.id);
+    });
+
+    return items;
+  }
+
+  /// 단건 조회. Preview 화면 진입 시.
+  Future<CatalogItem?> byId(String id) async {
+    final all_ = await all();
+    for (final item in all_) {
+      if (item.id == id) return item;
+    }
+    return null;
+  }
+
+  /// reference id 리스트 → References 테이블 매칭. 미매칭 항목은 결과에서 누락.
+  Future<List<ReferenceRow>> referencesByIds(List<String> ids) async {
+    if (ids.isEmpty) return const [];
+    return (_db.select(_db.references)..where((t) => t.id.isIn(ids))).get();
+  }
+}
+
+/// `what` 의 첫 문장을 추출. 비어있으면 `fallback` 사용. 60자 초과 시 절단.
+String _summary(String what, {required String fallback, int max = 60}) {
+  final firstSentence = what.split(RegExp(r'[.!?。！？]')).first.trim();
+  final s = firstSentence.isEmpty ? fallback : firstSentence;
+  return s.length <= max ? s : '${s.substring(0, max - 1)}…';
+}
+
+List<String> _decodeIds(String? jsonStr) {
+  if (jsonStr == null) return const [];
+  final decoded = jsonDecode(jsonStr);
+  return decoded is List ? decoded.cast<String>() : const [];
+}
+
+List<String> _decodeList(String? jsonStr) {
+  if (jsonStr == null) return const [];
+  final decoded = jsonDecode(jsonStr);
+  return decoded is List ? decoded.map((e) => e.toString()).toList() : const [];
+}
+
+Map<String, dynamic>? _decodeAnchor(String? jsonStr) {
+  if (jsonStr == null) return null;
+  final decoded = jsonDecode(jsonStr);
+  return decoded is Map<String, dynamic> ? decoded : null;
+}