feat(landing): link files. share from nav + hero

Read-only file browse was only reachable by typing the URL. Add
site.filesUrl (files.${BASE_DOMAIN}) plus nav/hero labels in en/es/eu,
and surface it as a nav link and a secondary hero CTA beside "Cómo entrar".

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

landing/src/pages/[...lang].astro

@@ -70,6 +70,7 @@ const dustBits = Array.from({ length: 16 }, (_, i) => {
         </a>
         <nav class="nav-links">
           <a href="#join">{t.nav.join}</a>
+          <a href={site.filesUrl} target="_blank" rel="noopener">{t.nav.files}</a>
           <a href="#status">{t.nav.status}</a>
         </nav>
         <span class="nav-spacer"></span>
@@ -106,6 +107,7 @@ const dustBits = Array.from({ length: 16 }, (_, i) => {
             <p class="hero-sub">{t.hero.sub}</p>
             <div class="hero-ip-row">
               <a class="mc-btn primary" href="#join">{t.hero.howToJoin}</a>
+              <a class="mc-btn" href={site.filesUrl} target="_blank" rel="noopener">{t.hero.files}</a>
             </div>
             <div class="hero-meta">
               <span>Java {site.mcVersion}</span>