feat(run-detail): add expandable step output blocks with json pretty-printing

- add collapsible code blocks for step output with JSON syntax highlighting
- display byte count when output exists but no description available
- support both individual row expansion and header-level expand all toggle
- pretty-print JSON output for improved readability
- wrap log messages in code tags for monospace display
- fix step order numbering to start from 1 instead of 2

client/src/pages/run/RunDetailPage.tsx

@@ -17,6 +17,7 @@ import {
   Badge,
   Breadcrumbs,
   Card,
+  CodeBlock,
   DescriptionList,
   Notification,
   Pagination,
@@ -27,7 +28,7 @@ import {
   type TableColumn,
 } from '../../ui';
 import type { BadgeVariant } from '../../ui';
-import { ClipboardList, Activity } from 'lucide-react';
+import { ChevronDown, ChevronRight, ClipboardList, Activity } from 'lucide-react';
 import styles from '../Page.module.css';
 
 const RUN_STATUS_VARIANT: Record<ScenarioRunStatus, BadgeVariant> = {
@@ -75,6 +76,8 @@ export function RunDetailPage() {
   const [logPage, setLogPage] = useState(1);
   const [logSearch, setLogSearch] = useState('');
   const [debouncedSearch, setDebouncedSearch] = useState('');
+  const [expandAll, setExpandAll] = useState(false);
+  const [expandedStepIds, setExpandedStepIds] = useState<Set<string>>(new Set());
   const logSearchRef = useRef('');
   const LOG_PAGE_SIZE = 25;
   const pollRef = useRef<ReturnType<typeof setInterval> | null>(null);
@@ -154,7 +157,7 @@ export function RunDetailPage() {
   }, [id, runId]);
 
   const stepColumns: TableColumn<ScenarioRunStep>[] = [
-    { key: 'order', header: t('runs.step_order'), render: (s) => s.order + 1, width: 50 },
+    { key: 'order', header: t('runs.step_order'), render: (s) => s.order, width: 50 },
     {
       key: 'title',
       header: t('runs.step_title'),
@@ -171,8 +174,97 @@ export function RunDetailPage() {
     },
     {
       key: 'description',
-      header: t('runs.step_description'),
+      header: (
-      render: (s) => s.description ?? <span className={styles.muted}>–</span>,
+        <div style={{ display: 'flex', alignItems: 'center', justifyContent: 'space-between', gap: '8px' }}>
+          <span>{t('runs.step_description')}</span>
+          {run?.stepRuns.some((s) => s.output) && (
+            <button
+              onClick={() => {
+                if (expandAll) {
+                  setExpandAll(false);
+                  setExpandedStepIds(new Set());
+                } else {
+                  setExpandAll(true);
+                  setExpandedStepIds(new Set(run?.stepRuns.filter((s) => s.output).map((s) => s.id) ?? []));
+                }
+              }}
+              style={{
+                background: 'none',
+                border: 'none',
+                padding: '0 4px',
+                cursor: 'pointer',
+                display: 'flex',
+                alignItems: 'center',
+                color: 'inherit',
+              }}
+              title={expandAll ? 'Collapse all' : 'Expand all'}
+            >
+              {expandAll ? <ChevronDown size={16} /> : <ChevronRight size={16} />}
+            </button>
+          )}
+        </div>
+      ),
+      render: (s) => {
+        const isExpanded = expandAll || expandedStepIds.has(s.id);
+        return (
+          <div>
+            <div style={{ display: 'flex', alignItems: 'flex-start', gap: '8px', marginBottom: isExpanded && s.output ? '8px' : 0 }}>
+              {s.output && (
+                <button
+                  onClick={() => {
+                    const newSet = new Set(expandedStepIds);
+                    if (newSet.has(s.id)) {
+                      newSet.delete(s.id);
+                    } else {
+                      newSet.add(s.id);
+                    }
+                    setExpandedStepIds(newSet);
+                  }}
+                  style={{
+                    background: 'none',
+                    border: 'none',
+                    padding: 0,
+                    cursor: 'pointer',
+                    display: 'flex',
+                    alignItems: 'center',
+                    flexShrink: 0,
+                    marginTop: '2px',
+                  }}
+                >
+                  {isExpanded ? (
+                    <ChevronDown size={16} />
+                  ) : (
+                    <ChevronRight size={16} />
+                  )}
+                </button>
+              )}
+              <code style={{ wordBreak: 'break-word' }}>
+                {s.description ? (
+                  s.description
+                ) : s.output ? (
+                  <span title={`${s.output.length} bytes`}>{s.output.length} bytes</span>
+                ) : (
+                  <span className={styles.muted}>–</span>
+                )}
+              </code>
+            </div>
+            {isExpanded && s.output && (
+              <div style={{ marginLeft: '24px' }}>
+                <CodeBlock 
+                  code={(() => {
+                    try {
+                      return JSON.stringify(JSON.parse(s.output), null, 2);
+                    } catch {
+                      return s.output;
+                    }
+                  })()} 
+                  language="json" 
+                />
+              </div>
+            )}
+          </div>
+        );
+      },
     },
   ];
 
@@ -183,7 +275,7 @@ export function RunDetailPage() {
       width: 70,
       render: (l) => <Badge variant={LOG_LEVEL_VARIANT[l.level]}>{l.level}</Badge>,
     },
-    { key: 'message', header: t('runs.log_message'), render: (l) => l.message },
+    { key: 'message', header: t('runs.log_message'), render: (l) => <code style={{ wordBreak: 'break-word' }}>{l.message}</code> },
     {
       key: 'time',
       header: t('runs.log_time'),