fix: 用 IntersectionObserver 替代 scroll 事件实现瀑布流

scroll 事件在某些布局下不触发，改用 IntersectionObserver
监听列表底部哨兵元素，进入视口时自动加载下一页，更可靠。

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/modules/mileage/MonitoringView.tsx

@@ -115,8 +115,6 @@ export default function MonitoringView() {
   const [loadingMore, setLoadingMore] = useState(false);
   const [showBackToTop, setShowBackToTop] = useState(false);
   const PAGE_SIZE = 50;
-  const listEndRef = useRef<HTMLDivElement>(null);
-  const scrollContainerRef = useRef<HTMLDivElement>(null);
 
   const departments = filterOptions.departments;
   const plateNumbers = filterOptions.plates;
@@ -178,26 +176,34 @@ export default function MonitoringView() {
     loadFirstPage();
   }, [loadFirstPage]);
 
-  // 滚动触底检测 + 回到顶部按钮
+  // 触底检测：用 IntersectionObserver 监听哨兵元素
   const loadMoreRef = useRef(loadMore);
   loadMoreRef.current = loadMore;
+  const sentinelRef = useRef<HTMLDivElement>(null);
 
+  useEffect(() => {
+    const sentinel = sentinelRef.current;
+    if (!sentinel) return;
+    const observer = new IntersectionObserver(
+      (entries) => {
+        if (entries[0].isIntersecting) {
+          loadMoreRef.current();
+        }
+      },
+      { rootMargin: '200px' }
+    );
+    observer.observe(sentinel);
+    return () => observer.disconnect();
+  }, []);
+
+  // 回到顶部按钮
   useEffect(() => {
     const handleScroll = () => {
       const scrollY = window.scrollY || document.documentElement.scrollTop;
       setShowBackToTop(scrollY > 400);
-      const scrollHeight = document.documentElement.scrollHeight;
-      const clientHeight = window.innerHeight;
-      if (scrollHeight - scrollY - clientHeight < 300) {
-        loadMoreRef.current();
-      }
     };
     window.addEventListener('scroll', handleScroll, { passive: true });
-    document.addEventListener('scroll', handleScroll, { passive: true });
-    return () => {
-      window.removeEventListener('scroll', handleScroll);
-      document.removeEventListener('scroll', handleScroll);
-    };
+    return () => window.removeEventListener('scroll', handleScroll);
   }, []);
 
   const scrollToTop = () => {
@@ -802,7 +808,8 @@ export default function MonitoringView() {
             <span className="text-[10px] font-bold text-slate-300">已加载全部 {total} 条</span>
           </div>
         )}
-        <div ref={listEndRef} />
+        {/* 哨兵元素：进入视口时触发加载更多 */}
+        <div ref={sentinelRef} className="h-1" />
       </div>
 
       {/* 回到顶部按钮 */}