fix(inventory): 修复库存数量字段精度处理问题

- 修改了QtyOnHand字段的查询逻辑，添加ROUND函数确保数值精度为3位小数
- 对空值进行ISNULL处理，避免数据库中null值导致的计算异常
- 确保库存数量显示的一致性和准确性

src/main/resources/mapper/pms/InventoryStockMapper.xml

@@ -221,7 +221,7 @@
         p.PartDescription AS partDescription,
         istk.BatchNo AS batchNo,
         istk.LocationID AS locationId,
-        istk.QtyOnHand AS qtyOnHand,
+        ROUND(ISNULL(istk.QtyOnHand, 0), 3) AS qtyOnHand,
         istk.FirstInDate AS firstInDate,
         istk.LatestOutDate AS latestOutDate,
         istk.LatestInDate AS latestInDate,