style：历史记录查询/数据实时监控-数据为null时显示-

src/views/iot/historyData/HistorySingleDeviceDialog.vue

@@ -191,7 +191,7 @@ const buildSectionsFromGroups = (groups: Record<string, any[]>): Section[] => {
         const label =
           item?.attributeName ?? `${t('DataCollection.HistoryData.defaultFieldLabelPrefix')}${index + 1}`
         columns.push({ prop, label })
-        row[prop] = item?.addressValue ?? ''
+        row[prop] = item?.addressValue ?? '-'
       })
     }
     result.push({

src/views/iot/realTimeMonitoring/SingleDeviceMonitorDialog.vue

@@ -147,7 +147,7 @@ const buildSectionsFromGroups = (groups: Record<string, any[]>): Section[] => {
         const label =
           item?.attributeName ?? `${t('DataCollection.RealTimeMonitoring.defaultFieldLabelPrefix')}${index + 1}`
         columns.push({ prop, label })
-        row[prop] = item?.addressValue ?? ''
+        row[prop] = item?.addressValue ?? '-'
       })
     }
     result.push({