fix: 搜索面板标签可再次点击取消(toggle)

再次点击已选中的标签时清空选中/查询/结果,而不是永久停留在该标签。

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

src/components/SearchPanel.tsx

@@ -106,6 +106,13 @@ export function SearchPanel({
   }, [langParam]);
 
   const showTagPosts = (tag: string) => {
+    // Tapping the active tag again clears it (toggle) instead of staying stuck.
+    if (selectedTag === tag) {
+      setSelectedTag("");
+      setTagPosts([]);
+      onQueryChange("");
+      return;
+    }
     setSelectedTag(tag);
     onQueryChange(tag);
     const searchUrl = buildSearchUrl({