feat: Add packages/site — landing vitrine (Vue 3 + Tailwind 4)

- Scaffold packages/site with 11 Vue components: hero (animated terminal), features, showcase, work groups, how-it-works, security, FAQ accordion, footer
- i18n EN/FR via vue-i18n with 82+ keys, autodetect navigator.language, toggle without reload
- Animated timeline (terminal, dialog, toast) ported from design, scroll-reveal, copy buttons (2 instances)
- Self-hosted JetBrains Mono fonts (@fontsource), optimized assets (mark 28KB, og-cover 1200×630)
- SEO: canonical, og:image, theme-color, robots.txt, sitemap.xml for git-arboretum.com
- Monorepo integration (decoupled from npm release): build:site / dev:site / preview:site scripts
- CI: add build:site step to ci.yml for early detection; create .gitea/workflows/prod.yml for FTPS deploy (lftp mirror) to git-arboretum.com
- Validated builds ✓ and UI rendering (EN/FR headless test) ✓

packages/site/public/icon.svg

@@ -0,0 +1,46 @@
+<svg xmlns="http://www.w3.org/2000/svg" width="512" height="512" viewBox="0 0 512 512" role="img" aria-label="Arboretum">
+  <defs>
+    <!-- glow néon : flou doux derrière les traits et les nœuds -->
+    <filter id="glow" x="-30%" y="-30%" width="160%" height="160%">
+      <feGaussianBlur stdDeviation="6" result="b"/>
+      <feMerge><feMergeNode in="b"/><feMergeNode in="SourceGraphic"/></feMerge>
+    </filter>
+    <linearGradient id="branch" x1="256" y1="430" x2="256" y2="90" gradientUnits="userSpaceOnUse">
+      <stop offset="0" stop-color="#10b981"/>
+      <stop offset="1" stop-color="#34d399"/>
+    </linearGradient>
+  </defs>
+
+  <rect width="512" height="512" fill="#09090b"/>
+
+  <!-- branches / circuit (tronc + fourches symétriques), tracées dans la zone sûre maskable -->
+  <g fill="none" stroke="url(#branch)" stroke-width="17" stroke-linecap="round" stroke-linejoin="round" filter="url(#glow)">
+    <!-- tronc : du nœud sommet jusqu'à la base avec le curseur >_ -->
+    <path d="M256 96 V392"/>
+    <!-- paire haute -->
+    <path d="M256 232 L150 232 V150"/>
+    <path d="M256 232 L362 232 V150"/>
+    <!-- paire médiane -->
+    <path d="M256 300 L104 300 V214"/>
+    <path d="M256 300 L408 300 V214"/>
+    <!-- paire basse -->
+    <path d="M256 356 L150 356 V300"/>
+    <path d="M256 356 L362 356 V300"/>
+    <!-- base : invite de commande >_ -->
+    <path d="M232 404 L246 418 L232 432" stroke-width="14"/>
+    <path d="M258 434 H286" stroke-width="14"/>
+  </g>
+
+  <!-- nœuds (sessions) : anneaux cyan lumineux, centre sombre -->
+  <g filter="url(#glow)">
+    <g fill="#09090b" stroke="#22d3ee" stroke-width="9">
+      <circle cx="256" cy="96"  r="20"/>
+      <circle cx="150" cy="150" r="16"/>
+      <circle cx="362" cy="150" r="16"/>
+      <circle cx="104" cy="214" r="16"/>
+      <circle cx="408" cy="214" r="16"/>
+      <circle cx="150" cy="300" r="16"/>
+      <circle cx="362" cy="300" r="16"/>
+    </g>
+  </g>
+</svg>

packages/site/public/robots.txt

@@ -0,0 +1,4 @@
+User-agent: *
+Allow: /
+
+Sitemap: https://git-arboretum.com/sitemap.xml

packages/site/public/sitemap.xml

@@ -0,0 +1,9 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<urlset xmlns="http://www.sitemaps.org/schemas/sitemap/0.9">
+  <url>
+    <loc>https://git-arboretum.com/</loc>
+    <lastmod>2026-06-19</lastmod>
+    <changefreq>monthly</changefreq>
+    <priority>1.0</priority>
+  </url>
+</urlset>