fix(prisma): drop owner FK before making ownerId NOT NULL

backend/prisma/migrations/20260502160000_product_owner_required/migration.sql

@@ -10,11 +10,7 @@ WHERE p.`ownerId` IS NULL;
 -- (InventoryItem, PantryItem, ReceiptAlias, ProductTag, Nutrition, UserProduct)
 DELETE FROM `Product` WHERE `ownerId` IS NULL;
 
--- Steg 3: Gör ownerId obligatoriskt
-ALTER TABLE `Product`
-  MODIFY COLUMN `ownerId` INT NOT NULL;
-
--- Steg 4: Uppdatera foreign key constraint till CASCADE
+-- Steg 3: Uppdatera foreign key constraint (droppa befintlig först)
 -- Droppa befintlig FK på ownerId med dynamiskt namn (miljöer kan skilja sig).
 SET @fk_name := (
   SELECT kcu.CONSTRAINT_NAME
@@ -36,6 +32,11 @@ PREPARE stmt_drop_fk FROM @drop_fk_sql;
 EXECUTE stmt_drop_fk;
 DEALLOCATE PREPARE stmt_drop_fk;
 
+-- Steg 4: Gör ownerId obligatoriskt
+ALTER TABLE `Product`
+  MODIFY COLUMN `ownerId` INT NOT NULL;
+
+-- Steg 5: Lägg tillbaka owner-FK med ON DELETE CASCADE
 ALTER TABLE `Product`
   ADD CONSTRAINT `Product_ownerId_fkey`
   FOREIGN KEY (`ownerId`) REFERENCES `User`(`id`)