[Developer] #204 Phase 1 MVP — Flutter app skeleton complete

- Drift 21 tables (8 catalog + 11 user + habit_dose_variants + meta_kv)
  with R1~R10 CHECK constraints and 19 indexes
- 8 hand-crafted seed JSON catalogs in app/assets/seed/
  (refs 84, protocols 34, methodologies 21, frame_patterns 30,
   reward_menu_items 30, break_protocols 8, common_frames 5, diet_patterns 5)
- 6 domain functions: recommend_variant, compute_streak,
  validate_frame_level, active_habit_quota, weekly_minimum_ratio,
  seed_importer (transactional, idempotent)
- 4 vertical-slice Riverpod screens: HabitList, HabitCreate, CheckIn, Streak
- 31 unit tests passing; flutter analyze clean
- OQ-5 streak semantics: missing entry ≠ explicit blank
  (missing = end of history; only TrackerValue.blank triggers Never-miss-twice)

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

app/lib/domain/models/phase.dart

@@ -0,0 +1,23 @@
+enum PhaseStatus { active, completed, abandoned }
+
+class PhaseModel {
+  final String id;
+  final String userId;
+  final String? title;
+  final String startedAt; // YYYY-MM-DD
+  final String? endedAt;
+  final int durationWeeks;
+  final PhaseStatus status;
+  final bool rewardDeclarationsLocked;
+
+  const PhaseModel({
+    required this.id,
+    required this.userId,
+    this.title,
+    required this.startedAt,
+    this.endedAt,
+    this.durationWeeks = 6,
+    required this.status,
+    this.rewardDeclarationsLocked = false,
+  });
+}