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/features/scan/recognition_confirm_screen.dart

@@ -2,7 +2,7 @@ import 'package:flutter/material.dart';
 import 'package:flutter_riverpod/flutter_riverpod.dart';
 
 import '../../core/locale/unit_provider.dart';
-import '../products/product_provider.dart';
+import '../products/user_product_provider.dart';
 import 'recognition_service.dart';
 
 /// Editable confirmation screen shown after receipt/products recognition.
@@ -31,7 +31,7 @@ class _RecognitionConfirmScreenState
               quantity: item.quantity,
               unit: item.unit,
               category: item.category,
-              mappingId: item.mappingId,
+              primaryProductId: item.primaryProductId,
               storageDays: item.storageDays,
               confidence: item.confidence,
             ))
@@ -83,13 +83,13 @@ class _RecognitionConfirmScreenState
     setState(() => _saving = true);
     try {
       for (final item in _items) {
-        await ref.read(productsProvider.notifier).create(
+        await ref.read(userProductsProvider.notifier).create(
               name: item.name,
               quantity: item.quantity,
               unit: item.unit,
               category: item.category,
               storageDays: item.storageDays,
-              mappingId: item.mappingId,
+              primaryProductId: item.primaryProductId,
             );
       }
       if (mounted) {
@@ -123,7 +123,7 @@ class _EditableItem {
   double quantity;
   String unit;
   final String category;
-  final String? mappingId;
+  final String? primaryProductId;
   final int storageDays;
   final double confidence;
 
@@ -132,7 +132,7 @@ class _EditableItem {
     required this.quantity,
     required this.unit,
     required this.category,
-    this.mappingId,
+    this.primaryProductId,
     required this.storageDays,
     required this.confidence,
   });