feat(site): center sponsors intro line and drop the visible heading

docs/app/[lang]/sponsors/page.tsx

@@ -160,8 +160,9 @@ export default async function SponsorsPage({ params }: { params: Promise<{ lang:
       <LandingNav lang={locale} active="sponsors" />
 
       <section className="max-w-[1180px] mx-auto px-6 pt-32 pb-24">
-        <h1 className="text-4xl font-[820] tracking-tight">{t.title}</h1>
-        <p className="mt-3 max-w-[700px] text-landing-muted text-lg leading-relaxed">{t.desc}</p>
+        {/* 视觉隐藏：页面不再展示大标题，但保留语义 landmark 与 SEO */}
+        <h1 className="sr-only">{t.title}</h1>
+        <p className="mx-auto max-w-[700px] text-center text-landing-muted text-lg leading-relaxed">{t.desc}</p>
 
         <h2 className="mt-10 text-2xl font-[760]">{t.sponsorsTitle}</h2>
         <div className="mt-5 grid grid-cols-2 gap-5 max-[900px]:grid-cols-1">