⚡ 维修记录里程单位改由车船类型自动推导，表单去掉里程单位项

- 里程/航程数标签去掉「（公里）」，表头不再需要 renderHeader 覆盖
- 里程单位列不再出现在表单（display: false），无需人工选择
- 单位仍按车船类型推导：车辆=公里、船舶=海里，保存时再兜底推导一次

src/views/vehicle/maintenance-record.vue

@@ -371,9 +371,8 @@ export default {
             placeholder: '日期时间选择器',
           },
           {
-            label: '里程/航程数（公里）',
+            label: '里程/航程数',
             prop: 'mileage',
-            renderHeader: () => '里程/航程数',
             type: 'input',
             minWidth: 130,
             slot: true,
@@ -391,6 +390,7 @@ export default {
             ],
             value: '公里',
             hide: true,
+            display: false,
           },
           {
             label: '备注',
@@ -565,12 +565,10 @@ export default {
       const mileageUnit = vehicleType === '船舶' ? '海里' : '公里';
       const vehicleTypeColumn = this.findColumn(this.option.column, 'vehicleType');
       const vehicleNoColumn = this.findColumn(this.option.column, 'vehicleNo');
-      const mileageColumn = this.findColumn(this.option.column, 'mileage');
       const mileageUnitColumn = this.findColumn(this.option.column, 'mileageUnit');
       vehicleNoColumn.placeholder =
         vehicleType === '船舶' ? '请选择船号' : '请选择车牌号';
       vehicleTypeColumn.disabled = Boolean(this.form.id);
-      mileageColumn.label = `里程/航程数（${mileageUnit}）`;
       mileageUnitColumn.value = mileageUnit;
       this.form.mileageUnit = mileageUnit;
       if (!this.isDetailLoading && oldValue && vehicleType !== oldValue) {