feat(ux): U1 虚拟滚动 — Pod/事件/审计/命令列表大数据量渲染优化

- 安装 @tanstack/react-virtual@3.14.4
- 新增 hooks/useVirtualRows.ts 可复用虚拟滚动 Hook
- PodsTab: 全量渲染→虚拟滚动, 支持 1000+ Pod + 动态行高(展开行)
- EventTable: 移除 maxRows=200 截断, 万级事件流畅渲染
- AuditOperationsTab: shadcn Table→虚拟滚动 CSS Grid 布局
- SessionCommandsPanel: 虚拟滚动, page_size 200→500
- npm run build ✅, tsc --noEmit ✅, 17/17 集成测试通过

frontend/src/hooks/useVirtualRows.ts

@@ -0,0 +1,74 @@
+// useVirtualRows — 虚拟滚动 Hook，基于 @tanstack/react-virtual
+// 用于大列表（1000+ 行）场景的性能优化，只渲染可见区域的行
+// 用法:
+//   const { scrollRef, virtualRows, totalHeight } = useVirtualRows({
+//     count: data.length, estimateSize: () => 40, overscan: 10,
+//   });
+import { useRef, useCallback } from 'react';
+import { useVirtualizer } from '@tanstack/react-virtual';
+
+export interface VirtualRowsOptions {
+  count: number;
+  estimateSize: (index: number) => number;
+  overscan?: number;
+  /** 滚动容器的 padding 顶部像素（影响虚拟化偏移计算） */
+  paddingTop?: number;
+}
+
+export interface VirtualRowsResult {
+  /** 绑定到滚动容器 div 的 ref */
+  scrollRef: React.RefObject<HTMLDivElement>;
+  /** 当前可见+overscan 范围内的虚拟行 */
+  virtualRows: ReturnType<ReturnType<typeof useVirtualizer>['getVirtualItems']>;
+  /** 虚拟容器的总高度（用于设置 spacer 高度） */
+  totalHeight: number;
+  /** 滚动到指定 index */
+  scrollToIndex: (index: number) => void;
+}
+
+/**
+ * 虚拟滚动 Hook
+ *
+ * ```tsx
+ * const { scrollRef, virtualRows, totalHeight } = useVirtualRows({
+ *   count: items.length, estimateSize: () => 40, overscan: 8,
+ * });
+ * return (
+ *   <div ref={scrollRef} style={{ height: 500, overflow: 'auto' }}>
+ *     <div style={{ height: totalHeight, position: 'relative' }}>
+ *       {virtualRows.map(vr => (
+ *         <div key={vr.key} style={{ position: 'absolute', top: vr.start, height: vr.size, width: '100%' }}>
+ *           {renderRow(items[vr.index])}
+ *         </div>
+ *       ))}
+ *     </div>
+ *   </div>
+ * );
+ * ```
+ */
+export function useVirtualRows({
+  count,
+  estimateSize,
+  overscan = 8,
+}: VirtualRowsOptions): VirtualRowsResult {
+  const scrollRef = useRef<HTMLDivElement>(null);
+
+  const virtualizer = useVirtualizer({
+    count,
+    getScrollElement: () => scrollRef.current,
+    estimateSize,
+    overscan,
+  });
+
+  const virtualRows = virtualizer.getVirtualItems();
+  const totalHeight = virtualizer.getTotalSize();
+
+  const scrollToIndex = useCallback(
+    (index: number) => {
+      virtualizer.scrollToIndex(index, { align: 'start' });
+    },
+    [virtualizer],
+  );
+
+  return { scrollRef, virtualRows, totalHeight, scrollToIndex };
+}