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>

backend/internal/domain/home/handler.go

@@ -76,12 +76,21 @@ func (h *Handler) getDailyGoal(ctx context.Context, userID string) int {
 }
 
 // getLoggedCalories returns total calories logged in meal_diary for today.
+// Supports both recipe-based entries (via recipes JOIN) and catalog product entries (via products JOIN).
 func (h *Handler) getLoggedCalories(ctx context.Context, userID, date string) float64 {
 	var total float64
 	_ = h.pool.QueryRow(ctx,
-		`SELECT COALESCE(SUM(calories * portions), 0)
-		 FROM meal_diary
-		 WHERE user_id = $1 AND date::text = $2`,
+		`SELECT COALESCE(SUM(
+			COALESCE(
+				r.calories_per_serving * md.portions,
+				p.calories_per_100g   * md.portion_g / 100,
+				0
+			)
+		), 0)
+		FROM meal_diary md
+		LEFT JOIN recipes r ON r.id = md.recipe_id
+		LEFT JOIN products p ON p.id = md.product_id
+		WHERE md.user_id = $1 AND md.date::text = $2`,
 		userID, date,
 	).Scan(&total)
 	return total
@@ -153,7 +162,7 @@ func (h *Handler) getExpiringSoon(ctx context.Context, userID string) []Expiring
 		WITH p AS (
 			SELECT name, quantity, unit,
 			       (added_at + storage_days * INTERVAL '1 day') AS expires_at
-			FROM products
+			FROM user_products
 			WHERE user_id = $1
 		)
 		SELECT name, quantity, unit,