fix: 创建商品时自动创建库存记录(初始为0)

src/main/java/com/example/building/service/impl/ProductServiceImpl.java

@@ -133,6 +133,15 @@ public class ProductServiceImpl implements ProductService {
         product.setProductId(UUID.randomUUID().toString());
         product.setStatus(1);
         productMapper.insert(product);
+        
+        // 创建商品时自动创建库存记录
+        Stock stock = new Stock();
+        stock.setStockId(UUID.randomUUID().toString());
+        stock.setProductId(product.getProductId());
+        stock.setQuantity(0);
+        stock.setLockedQuantity(0);
+        stockMapper.insert(stock);
+        
         return product;
     }