refactor(tables): share parent column grid in expandable child rows

- llmodels/model-routes/cluster child rows use ExpandedRowGrid + Cell
  (auto-flow spans, no parent-key/grid-line math)
- define --seal-table-row-min-height token in global.less
- routes created_at column: span -> fixed width 180

src/pages/model-routes/hooks/use-routes-columns.tsx

@@ -232,7 +232,7 @@ const useAccessColumns = ({
         title: intl.formatMessage({ id: 'common.table.createTime' }),
         dataIndex: 'created_at',
         sorter: tableSorter(6),
-        span: createTimeSpan,
+        width: 180,
         render: (value: string) => (
           <AutoTooltip ghost minWidth={20}>
             {dayjs(value).format('YYYY-MM-DD HH:mm:ss')}