fix(wms/material): 修正钢卷长度字段为整型

将WmsMaterialCoil及相关BO/VO中的length和actualLength字段从BigDecimal改为Long类型，并在WmsCoilPendingActionServiceImpl和WmsCoilWarehouseOperationLogServiceImpl中相应调整赋值逻辑，确保类型转换时进行空值检查，避免空指针异常。

klp-wms/src/main/java/com/klp/service/impl/WmsCoilPendingActionServiceImpl.java

@@ -303,7 +303,7 @@ public class WmsCoilPendingActionServiceImpl implements IWmsCoilPendingActionSer
                     // 净重 > 毛重
                     plan.setInMatWeight(coil.getNetWeight() != null ? coil.getNetWeight() : coil.getGrossWeight());
                     // 长度
-                    plan.setInMatLength(coil.getLength());
+                    plan.setInMatLength(coil.getLength() != null ? BigDecimal.valueOf(coil.getLength()) : null);
 
                     // ② 查原材料库（itemType='raw_material' 时通过 itemId 关联）
                     if ("raw_material".equals(coil.getItemType()) && coil.getItemId() != null) {