polish(ui): 侧栏可点块悬停/聚焦统一为主题色淡底

Co-authored-by: Cursor <cursoragent@cursor.com>

frontend/components/home/BoardPanels.tsx

@@ -162,13 +162,10 @@ function BoardHot({ posts }: { posts: PostListItem[] }) {
         <ol className="j13-ranklist">
           {posts.map((p, i) => (
             <li key={p.id}>
-              <Link href={`/post/${p.id}`} className="j13-rank group" data-tip={p.title}>
+              <Link href={`/post/${p.id}`} className="j13-rank" data-tip={p.title}>
                 <span className="j13-rank-no">{i + 1}</span>
                 <span className="min-w-0 flex-1">
-                  <span
-                    className="block truncate text-[13px] font-medium leading-snug transition-colors group-hover:text-[var(--accent)]"
-                    style={{ color: "var(--ink)" }}
-                  >
+                  <span className="j13-rank-title truncate">
                     {p.title}
                   </span>
                   <span className="mt-1 flex items-center gap-2.5 meta text-[11.5px]">