feat: rename ingredients→products, products→user_products; add barcode/OFF import

- Rename catalog: ingredient/* → product/* (canonical_name, barcode, nutrition per 100g)
- Rename pantry: product/* → userproduct/* (user-owned items with expiry)
- Squash migrations into single 001_initial_schema.sql (clean-db baseline)
- product_categories: add English canonical name column; fix COALESCE in queries
- Remove product_translations: product names are stored in their original language
- Add default_unit_name to product API responses via unit_translations JOIN
- Add cmd/importoff: bulk import from OpenFoodFacts JSONL dump (COPY + ON CONFLICT)
- Diary: support product_id entries alongside dish_id (CHECK num_nonnulls = 1)
- Home: getLoggedCalories joins both recipes and catalog products
- Flutter: rename models/providers/services to match backend rename
- Flutter: add barcode scan flow for diary (mobile_scanner, product_portion_sheet)
- Flutter: localise 6 new keys across 12 languages (barcode scan, portion weight)
- Routes: GET /products/search, GET /products/barcode/{barcode}, /user-products

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

client/lib/shared/models/product.dart

@@ -2,45 +2,48 @@ import 'package:json_annotation/json_annotation.dart';
 
 part 'product.g.dart';
 
+/// Catalog product (shared nutrition database entry).
 @JsonSerializable()
-class Product {
+class CatalogProduct {
   final String id;
-  @JsonKey(name: 'user_id')
-  final String userId;
-  @JsonKey(name: 'mapping_id')
-  final String? mappingId;
-  final String name;
-  final double quantity;
-  final String unit;
+  @JsonKey(name: 'canonical_name')
+  final String canonicalName;
+  @JsonKey(name: 'category_name')
+  final String? categoryName;
   final String? category;
+  @JsonKey(name: 'default_unit')
+  final String? defaultUnit;
   @JsonKey(name: 'storage_days')
-  final int storageDays;
-  @JsonKey(name: 'added_at')
-  final DateTime addedAt;
-  @JsonKey(name: 'expires_at')
-  final DateTime expiresAt;
-  @JsonKey(name: 'days_left')
-  final int daysLeft;
-  @JsonKey(name: 'expiring_soon')
-  final bool expiringSoon;
+  final int? storageDays;
+  final String? barcode;
+  @JsonKey(name: 'calories_per_100g')
+  final double? caloriesPer100g;
+  @JsonKey(name: 'protein_per_100g')
+  final double? proteinPer100g;
+  @JsonKey(name: 'fat_per_100g')
+  final double? fatPer100g;
+  @JsonKey(name: 'carbs_per_100g')
+  final double? carbsPer100g;
 
-  const Product({
+  const CatalogProduct({
     required this.id,
-    required this.userId,
-    this.mappingId,
-    required this.name,
-    required this.quantity,
-    required this.unit,
+    required this.canonicalName,
+    this.categoryName,
     this.category,
-    required this.storageDays,
-    required this.addedAt,
-    required this.expiresAt,
-    required this.daysLeft,
-    required this.expiringSoon,
+    this.defaultUnit,
+    this.storageDays,
+    this.barcode,
+    this.caloriesPer100g,
+    this.proteinPer100g,
+    this.fatPer100g,
+    this.carbsPer100g,
   });
 
-  factory Product.fromJson(Map<String, dynamic> json) =>
-      _$ProductFromJson(json);
+  /// Display name is the server-resolved canonical name (language-aware from backend).
+  String get displayName => canonicalName;
 
-  Map<String, dynamic> toJson() => _$ProductToJson(this);
+  factory CatalogProduct.fromJson(Map<String, dynamic> json) =>
+      _$CatalogProductFromJson(json);
+
+  Map<String, dynamic> toJson() => _$CatalogProductToJson(this);
 }