Show version block in panorama node view

Why: the I4 scenarios assert the version collapsible for a selected
section in the panorama (not only the reader); the panorama node view
had no version block, so .cockpit-versions-toggle never existed there.
Also normalize null list projections in the panorama node detail fetch
(same Go nil-slice issue fixed for the panel earlier).

Evidence: tsc clean, vitest green, build green (SELF); seven-scenario
rerun to be recorded on the Dev I4 card.

Impact: cockpit panorama only.

Refs: rollout I4

src/components/DocumentCockpit.tsx

@@ -16,7 +16,7 @@ import {
   type CockpitTreeNode, type CockpitTreePage,
   type Density, type PanelTabId, type ViewMode,
 } from '../documentCockpit'
-import { CockpitPanel, CockpitReader } from './CockpitReader'
+import { CockpitPanel, CockpitReader, VersionBlock } from './CockpitReader'
 
 interface ProjectView { projectId: string; name: string; canAudit?: boolean }
 
@@ -198,6 +198,7 @@ export function DocumentCockpit() {
           {overview && selected && viewMode === 'panorama' && (
             <PanoramaNode pid={pid} selection={selected} overview={overview}
               childPage={selected.ref.kind === 'document' ? treePages[selected.ref.id] : undefined}
+              density={density}
               onClear={() => setSelected(null)}
               onOpenReader={() => applyPrefs({ lastView: 'reader' })} />
           )}
@@ -289,9 +290,10 @@ function PanoramaHome({ overview, onSelect }: { overview: CockpitOverview; onSel
   )
 }
 
-function PanoramaNode({ pid, selection, overview, childPage, onClear, onOpenReader }: {
+function PanoramaNode({ pid, selection, overview, childPage, density, onClear, onOpenReader }: {
   pid: string; selection: Selection; overview: CockpitOverview
   childPage?: { items: CockpitTreeNode[]; nextCursor?: string; hasMore: boolean; meta?: CockpitMeta }
+  density: Density
   onClear: () => void
   onOpenReader: () => void
 }) {
@@ -302,7 +304,14 @@ function PanoramaNode({ pid, selection, overview, childPage, onClear, onOpenRead
     const g = ++gen.current
     setDetail(null); setErr('')
     api.rdmCommand<any>('rdm.cockpit.node', { projectId: pid, kind: selection.ref.kind, id: selection.ref.id })
-      .then(d => { if (g === gen.current) setDetail(d) })
+      .then(d => {
+        if (g !== gen.current) return
+        // 后端空列表可能投影为 null（Go nil slice）；统一归一，消费端按数组使用。
+        for (const k of ['sources', 'history', 'impacts', 'conflicts'] as const) {
+          if (d?.[k] && !Array.isArray(d[k].items)) d[k].items = []
+        }
+        setDetail(d)
+      })
       .catch(e => { if (g === gen.current) setErr(e.message) })
     return () => { gen.current++ }
   }, [pid, selection.ref.kind, selection.ref.id])
@@ -320,6 +329,9 @@ function PanoramaNode({ pid, selection, overview, childPage, onClear, onOpenRead
       {detail?.body?.length === 1 && detail.body[0].kind === 'restricted' && (
         <div className="empty-note">内容受限（{detail.body[0].reason || '权限'}）——标题与状态可见，正文不展示</div>
       )}
+      {selection.ref.kind === 'section' && detail?.versions && detail.versions.length > 0 && (
+        <VersionBlock versions={detail.versions} density={density} />
+      )}
       {detail && detail.meta && !sameSnapshot(detail.meta, overview.meta) && (
         <div className="cockpit-truncated">节点详情与统计快照不同（{detail.meta.snapshotRevision} vs {overview.meta.snapshotRevision}）——刷新对齐</div>
       )}