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/src/composables/useHeroTimeline.ts

@@ -0,0 +1,113 @@
+import { onMounted, onUnmounted, ref } from 'vue';
+
+// Portage 1:1 de la timeline animée du mockup hero (Arboretum.dc.html).
+export type SessionState = 'idle' | 'busy' | 'waiting';
+
+export interface AnimLine {
+  text: string;
+  k: string;
+}
+
+export interface HeroAnim {
+  sess: SessionState;
+  lines: AnimLine[];
+  att: number;
+  toast: boolean;
+  dlg: boolean;
+  hl: number;
+  ans: number;
+  cur: boolean;
+}
+
+const TOTAL = 13000;
+const TICK = 80;
+
+interface ScriptEntry {
+  at: number;
+  text: string;
+  k: string;
+}
+
+function script(): ScriptEntry[] {
+  return [
+    { at: 850, text: '$ claude --resume feat/auth', k: 'cmd' },
+    { at: 1400, text: '> Reading src/auth/login.ts', k: 'tool' },
+    { at: 1950, text: '● Edit  login.ts', k: 'edit' },
+    { at: 2400, text: "  + import { verifyToken } from './jwt'", k: 'add' },
+    { at: 2850, text: '  + const user = await verifyToken(req)', k: 'add' },
+    { at: 3350, text: '● Bash  npm test -- auth', k: 'edit' },
+    { at: 3850, text: '  ✓ 14 passed (1.24s)', k: 'ok' },
+    { at: 4300, text: '● Permission required to edit login.ts', k: 'warn' },
+    { at: 7950, text: '✓ approved · applying change', k: 'ok' },
+    { at: 8500, text: '● Edit  login.ts', k: 'edit' },
+    { at: 9050, text: '● Running…', k: 'run' },
+  ];
+}
+
+export function deriveAnim(clock: number): HeroAnim {
+  const sess: SessionState = clock < 700 ? 'idle' : clock < 4500 ? 'busy' : clock < 7700 ? 'waiting' : 'busy';
+  const sc = script();
+  const lines: AnimLine[] = [];
+  for (const entry of sc) {
+    if (clock >= entry.at) lines.push({ text: entry.text, k: entry.k });
+  }
+  const att = clock >= 4500 && clock < 7700 ? 1 : 0;
+  const toast = clock >= 4650 && clock < 7700;
+  const dlg = clock >= 4600 && clock < 7700;
+  const hl = clock >= 6000 && clock < 7050 ? 0 : -1;
+  const ans = clock >= 7050 && clock < 7700 ? 0 : -1;
+  const cur = sess !== 'waiting';
+  return { sess, lines, att, toast, dlg, hl, ans, cur };
+}
+
+export function useHeroTimeline(stageId = 'hero-stage') {
+  const anim = ref<HeroAnim>(deriveAnim(0));
+  let clock = 0;
+  let visible = true;
+  let everVisible = false;
+  let timer: ReturnType<typeof setInterval> | undefined;
+  let io: IntersectionObserver | undefined;
+
+  onMounted(() => {
+    let reduced = false;
+    try {
+      reduced = window.matchMedia('(prefers-reduced-motion: reduce)').matches;
+    } catch {
+      /* ignore */
+    }
+    if (reduced) {
+      anim.value = deriveAnim(5200);
+      return;
+    }
+    const stage = document.getElementById(stageId);
+    if (stage && 'IntersectionObserver' in window) {
+      io = new IntersectionObserver(
+        (entries) => {
+          const e = entries[0];
+          if (!e) return;
+          if (e.isIntersecting) {
+            visible = true;
+            everVisible = true;
+          } else if (everVisible) {
+            visible = false;
+          }
+        },
+        { threshold: 0, rootMargin: '200px 0px 200px 0px' },
+      );
+      io.observe(stage);
+    }
+    timer = setInterval(() => {
+      if (!visible) return;
+      clock += TICK;
+      if (clock >= TOTAL) clock = 0;
+      anim.value = deriveAnim(clock);
+    }, TICK);
+  });
+
+  onUnmounted(() => {
+    if (timer) clearInterval(timer);
+    if (io) io.disconnect();
+  });
+
+  return { anim };
+}