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/pubspec.lock

@@ -717,6 +717,14 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "2.0.0"
+  mobile_scanner:
+    dependency: "direct main"
+    description:
+      name: mobile_scanner
+      sha256: "0b466a0a8a211b366c2e87f3345715faef9b6011c7147556ad22f37de6ba3173"
+      url: "https://pub.dev"
+    source: hosted
+    version: "6.0.11"
   mockito:
     dependency: "direct dev"
     description: