Normalize null list projections in cockpit node detail

Why: rdm.cockpit.node projects empty conflicts as items:null (Go nil
slice) while sources arrive as []; the panel read items.length on null
and crashed, so the conflicts empty state never rendered (I4 e2e
scenario 3).

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

Impact: cockpit panel only.

Refs: rollout I4

src/components/CockpitReader.tsx

@@ -36,7 +36,14 @@ function useNodeDetail(pid: string, sel?: CockpitNodeRef) {
     setDetail(null); setErr('')
     if (!sel) return
     api.rdmCommand<any>('rdm.cockpit.node', { projectId: pid, kind: sel.kind, id: sel.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, sel?.kind, sel?.id])