fix(FR-2380): show seconds in scheduling history timestamps (#6192)

Resolves #6169 (FR-2380)

## Summary
- Show seconds in scheduling history timestamps by changing dayjs format from `'ll LT'` to `'ll LTS'`
- Also update sub-step timestamps from `'lll'` to `'ll LTS'` for consistent second-level precision
- This helps users distinguish closely-timed scheduling events at a glance

![CleanShot 2026-03-26 at 21.08.05@2x.png](https://app.graphite.com/user-attachments/assets/ac16aa03-def4-424a-8a58-4d19fa22c74a.png)

## Changes
| File | Change |
|------|--------|
| `BAISchedulingHistoryNodes.tsx` | `updatedAt`, `createdAt`: `'ll LT'` → `'ll LTS'` |
| `BAISessionHistorySubStepNodes.tsx` | `startedAt`, `endedAt`: `'lll'` → `'ll LTS'` |

**Checklist:**

- [ ] Specific setting for review: Navigate to session scheduling history to verify timestamps now show seconds

Author: nowgnuesLee

packages/backend.ai-ui/src/components/fragments/BAISchedulingHistoryNodes.tsx

@@ -132,14 +132,14 @@ const BAISchedulingHistoryNodes = ({
         dataIndex: 'updatedAt',
         title: t('comp:BAISchedulingHistoryNodes.UpdatedAt'),
         key: 'updatedAt',
-        render: (value) => <span>{dayjs(value).format('ll LT')}</span>,
+        render: (value) => <span>{dayjs(value).format('ll LTS')}</span>,
         sorter: isEnableSorter('updated_at'),
       },
       {
         dataIndex: 'createdAt',
         title: t('comp:BAISchedulingHistoryNodes.CreatedAt'),
         key: 'createdAt',
-        render: (value) => <span>{dayjs(value).format('ll LT')}</span>,
+        render: (value) => <span>{dayjs(value).format('ll LTS')}</span>,
         sorter: isEnableSorter('created_at'),
       },
     ]),

packages/backend.ai-ui/src/components/fragments/BAISessionHistorySubStepNodes.tsx

@@ -122,15 +122,15 @@ const BAISessionHistorySubStepNodes = ({
         title: t('comp:SessionHistorySubStepNodes.StartedAt'),
         dataIndex: 'startedAt',
         render: (__, record) =>
-          record.startedAt ? dayjs(record.startedAt).format('lll') : '-',
+          record.startedAt ? dayjs(record.startedAt).format('ll LTS') : '-',
         sorter: isEnableSorter('startedAt'),
       },
       {
         key: 'endedAt',
         title: t('comp:SessionHistorySubStepNodes.EndedAt'),
         dataIndex: 'endedAt',
         render: (__, record) =>
-          record.endedAt ? dayjs(record.endedAt).format('lll') : '-',
+          record.endedAt ? dayjs(record.endedAt).format('ll LTS') : '-',
         sorter: isEnableSorter('endedAt'),
       },
     ]),