fix: gxnlpt 收起分类时自动滚动到该分类标题

收起后内容高度骤减,用户视野可能停留在下方空白区。
现在收起后 smooth scroll 到当前分类 header (留80px顶栏余量)。

Co-Authored-By: Claude <noreply@anthropic.com>

txw-mhzc-web/src/pages/index/views/gxnlpt/index.vue

@@ -1155,16 +1155,27 @@ export default {
     toggleViewMore(category) {
       const total = category.cardList.length;
       if (category.visibleCount >= total) {
-        // 已展开到底,收起回到初始预览数
+        // 收起：回到初始预览数，并滚动到当前分类标题
         category.visibleCount = category.previewSize;
+        this.refreshDisplayList(category);
+        this.$nextTick(() => {
+          const el = document.getElementById(category.id);
+          if (!el) return;
+          const scrollRoot = this.getScrollRoot();
+          if (!scrollRoot) return;
+          const rootRect = scrollRoot.getBoundingClientRect();
+          const elRect = el.getBoundingClientRect();
+          const target = scrollRoot.scrollTop + (elRect.top - rootRect.top) - 80;
+          scrollRoot.scrollTo({ top: Math.max(0, target), behavior: 'smooth' });
+        });
       } else {
         // 每次展开 previewSize 个,不超过 total
         category.visibleCount = Math.min(
           category.visibleCount + category.previewSize,
           total,
         );
+        this.refreshDisplayList(category);
       }
-      this.refreshDisplayList(category);
     },
     async loadAllSections() {
       this.pageLoading = true;