Default lot category to PART_ when missing

internal/warehouse/snapshot.go

@@ -85,12 +85,43 @@ func ComputePricelistItemsFromStockLog(db *gorm.DB) ([]SnapshotItem, error) {
 				}
 			}
 		}
+		defaultCategory := models.DefaultLotCategoryCode
+		missingCategoryLots := make([]string, 0)
+		for i := range items {
+			if strings.TrimSpace(items[i].Category) == "" {
+				items[i].Category = defaultCategory
+				missingCategoryLots = append(missingCategoryLots, items[i].LotName)
+			}
+		}
+		if len(missingCategoryLots) > 0 {
+			ensureCategoryExists(db, defaultCategory)
+			_ = db.Model(&models.Lot{}).
+				Where("lot_name IN ?", missingCategoryLots).
+				Update("lot_category", defaultCategory).Error
+		}
 	}
 
 	sort.Slice(items, func(i, j int) bool { return items[i].LotName < items[j].LotName })
 	return items, nil
 }
 
+func ensureCategoryExists(db *gorm.DB, code string) {
+	var count int64
+	if err := db.Model(&models.Category{}).Where("code = ?", code).Count(&count).Error; err != nil || count > 0 {
+		return
+	}
+	var maxOrder int
+	if err := db.Model(&models.Category{}).Select("COALESCE(MAX(display_order), 0)").Scan(&maxOrder).Error; err != nil {
+		return
+	}
+	_ = db.Create(&models.Category{
+		Code:         code,
+		Name:         code,
+		NameRu:       code,
+		DisplayOrder: maxOrder + 1,
+	}).Error
+}
+
 // LoadLotMetrics returns stock qty and partnumbers for selected lots.
 // If latestOnly is true, qty/partnumbers from stock_log are calculated only for latest import date.
 func LoadLotMetrics(db *gorm.DB, lotNames []string, latestOnly bool) (map[string]float64, map[string][]string, error) {