chore(frontend): about 页移除 QQ 群联系方式，仅保留微信群

QQ 群已不再活跃维护，关联展示也容易让用户搜不到。保留微信群入口即可。

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

BillNote_frontend/src/pages/SettingPage/about.tsx

@@ -198,10 +198,6 @@ export default function AboutPage() {
           <h2 className="mb-8 text-center text-3xl font-bold">联系和加入社区</h2>
           <div className="mx-auto max-w-3xl">
             <div className="flex flex-col items-center justify-center gap-8">
-              <div className="text-center">
-                <h3 className="mb-3 text-xl font-semibold">BiliNote 交流 QQ 群</h3>
-                <p className="text-lg font-medium">785367111</p>
-              </div>
               <div className="text-center">
                 <h3 className="mb-3 text-xl font-semibold">BiliNote 交流微信群</h3>
                 <div className="bg-muted mx-auto flex h-52 w-52 items-center justify-center rounded-md">