feat: initial commit - Habo habit tracking app

- Complete MVP with Repository Pattern, SQLite storage
- Provider + ChangeNotifier state management
- Navigation 2.0 with deep link support
- Habit CRUD with twoDayRule, notifications, categories
- Backup/Restore via JSON
- Statistics with streak tracking
- Material You theme support
- Biometric lock support
- Desktop widget support
- 27 languages i18n structure
- Comprehensive test suite (87/89 passing)

lib/model/backup.dart

@@ -0,0 +1,25 @@
+class BackupData {
+  final int version;
+  final List<Map<String, dynamic>> habits;
+  final List<Map<String, dynamic>> categories;
+  final List<Map<String, dynamic>> habitCategories;
+  final Map<String, dynamic> metadata;
+
+  BackupData({
+    this.version = 3,
+    this.habits = const [],
+    this.categories = const [],
+    this.habitCategories = const [],
+    this.metadata = const {},
+  });
+
+  Map<String, dynamic> toJson() {
+    return {
+      'version': version,
+      'habits': habits,
+      'categories': categories,
+      'habit_categories': habitCategories,
+      'metadata': metadata,
+    };
+  }
+}