feat(seo): make paca.chanpaca.net the canonical domain for the whole site

Both hostnames served the same sitemap and feed, so the sitemap submitted for
paca.chanpaca.net listed only mediabrowser.chanpaca.net URLs and Naver rejected
it as not matching the verified domain. Switch every canonical URL, Open Graph
tag, hreflang, JSON-LD, sitemap, RSS feed, llms files, app share link, package
manifest and promo UTM to paca.chanpaca.net, then resubmit the corrected Naver
and Search Console sitemaps. All 2,757 tests pass.

💘 Generated with Crush

Assisted-by: Crush:deepseek-v4.1-flash

site/releases.html

@@ -8,10 +8,10 @@
 <meta property="og:type" content="website">
 <meta property="og:title" content="Paca - 릴리스 &amp; 다운로드">
 <meta property="og:description" content="Windows 설치자와 macOS·Linux 프리뷰, Android APK 까지 Paca 의 모든 릴리스를 한곳에서 내려받으세요.">
-<meta property="og:url" content="https://mediabrowser.chanpaca.net/releases.html">
+<meta property="og:url" content="https://paca.chanpaca.net/releases.html">
 <meta name="theme-color" content="#08090d">
-<meta property="og:image" content="https://mediabrowser.chanpaca.net/assets/og.jpg">
-<link rel="canonical" href="https://mediabrowser.chanpaca.net/releases.html">
+<meta property="og:image" content="https://paca.chanpaca.net/assets/og.jpg">
+<link rel="canonical" href="https://paca.chanpaca.net/releases.html">
 <meta name="twitter:card" content="summary_large_image">
 <link rel="icon" href="assets/favicon.svg" type="image/svg+xml">
 <link rel="icon" href="assets/favicon-32x32.png" type="image/png">