polish(frontend): 修正中文字重发虚，并疏朗首页与数据区

补齐 Noto 600/800 并关闭伪粗；Header 加大加粗导航并加板块入口；去掉灰块底、加大列表行距，站点数据格居中缩小数字。

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

frontend/components/CommentSection.tsx

@@ -486,8 +486,8 @@ export default function CommentSection({
         </form>
       ) : (
         <div
-          className="mb-8 px-5 py-4 rounded-2xl flex items-center justify-between gap-4 flex-wrap"
-          style={{ background: "var(--panel-2)" }}
+          className="mb-8 px-5 py-4 rounded-2xl flex items-center justify-between gap-4 flex-wrap border"
+          style={{ borderColor: "var(--line)", background: "transparent" }}
         >
           <span className="text-sm" style={{ color: "var(--ink-2)" }}>
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