fix(log-center): 修复 demo 数据源、ES 502、查询页关联

frontend/src/components/monitor/log-center/UnifiedQueryPanel.tsx

@@ -132,12 +132,13 @@ export function UnifiedQueryPanel({ engine, onRuleCreated }: Props) {
   const meta = ENGINE_META[effEngine];
   const badge = ENGINE_BADGE[effEngine];
 
-  // 从后端加载真实数据源，无数据时用 demo 兜底 // Logan.Li
+  // 从后端加载真实数据源，同时保留 demo 兜底 // Logan.Li
   const [sources, setSources] = useState<LogDataSource[]>(DEMO_SOURCES[effEngine]);
   useEffect(() => {
     logCenterApi.listDatasources(effEngine).then((res: any) => {
       const list: LogDataSource[] = Array.isArray(res) ? res : (res?.list || []);
-      if (list.length > 0) setSources(list);
+      // 合并真实数据源 + demo 兜底（真实源在前） // Logan.Li
+      if (list.length > 0) setSources([...list, ...DEMO_SOURCES[effEngine]]);
       else setSources(DEMO_SOURCES[effEngine]);
     }).catch(() => setSources(DEMO_SOURCES[effEngine]));
   }, [effEngine]);
@@ -277,7 +278,7 @@ export function UnifiedQueryPanel({ engine, onRuleCreated }: Props) {
         <TimeRangePicker value={timeRange} onChange={setTimeRange} />
 
         <select value={dsId} onChange={e => setDsId(e.target.value)} className="h-10 px-2 text-xs rounded flex-shrink-0" style={{ background: 'var(--dg-bg-tertiary)', border: '1px solid var(--dg-border)', color: 'var(--dg-text-primary)' }}>
-          {sources.map(s => <option key={s.id} value={s.id}>{s.name}{isDemo ? ' (模拟)' : ''}</option>)}
+          {sources.map(s => <option key={s.id} value={s.id}>{s.name}{(s.id < 0 || !s.url) ? ' (模拟)' : ''}</option>)}
         </select>
 
         <button onClick={handleRun} disabled={loading} className="h-10 px-4 rounded text-xs font-medium text-white flex items-center gap-1.5 flex-shrink-0 transition-opacity hover:opacity-90" style={{ background: '#22c55e' }}>