feat(site): rewrite the landing page around verified facts and accessible controls

- Replace claims that contradicted the app: the default hotkey is Right Alt
  (hold to talk), local features are free with no daily cap, there is no
  14-day trial, Team/SSO/SCIM/ZDR are not offered, and the repository is not
  public. Remove invented metrics, status badges, the competitor table, the
  ad-mediation changelog, the hash calculator and the duplicate demo.
- Seven sections: hero with one labelled example, features, how it works,
  privacy, pricing (Free / Pro 2,900 / Pro+ 8,900 KRW a month), download, FAQ.
  Footer links the privacy policy, terms and account deletion pages.
- All copy moves into i18n and every one of the 10 locales is translated.
  Pricing and cloud quotas come from site/src/pricing.ts.
- Accessibility: skip link, labelled sections, aria-expanded with Esc and
  focus return for the menu, language list and FAQ, live status for the
  example, reduced-motion support, 44px targets, AA contrast on the primary
  button. Korean keep-all line breaking is scoped to :lang(ko) because
  Tailwind's break-keep blocked wrapping in Japanese and Chinese.
- JS 111 -> 98 KB gzip, CSS 7.8 -> 5.2 KB gzip.

site/src/components/SectionHeading.tsx

@@ -0,0 +1,20 @@
+interface SectionHeadingProps {
+  id: string
+  title: string
+  subtitle?: string
+  className?: string
+}
+
+/** 섹션 제목. `id`는 섹션의 aria-labelledby 대상이다. */
+export function SectionHeading({ id, title, subtitle, className = '' }: SectionHeadingProps) {
+  return (
+    <div className={className}>
+      <h2 id={id} className="keep-ko text-balance text-h2 font-medium text-neutral-50">
+        {title}
+      </h2>
+      {subtitle && (
+        <p className="mt-4 max-w-xl keep-ko text-base leading-relaxed text-neutral-300">{subtitle}</p>
+      )}
+    </div>
+  )
+}