✨ Add layouts, routing, transitions & pages (Story 1.4)

Default layout with sticky AppHeader (nav, LanguageSwitcher, mobile hamburger),
AppFooter with social links. Minimal layout for express mode. 7 placeholder pages
with localized EN routes. Page transitions (fade+slide), prefers-reduced-motion
support, custom scroll behavior, error.vue, useSeo composable, SVG favicon.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

frontend/app/pages/index.vue

@@ -1,14 +1,31 @@
 <template>
-  <div class="min-h-screen bg-sky-dark flex flex-col items-center justify-center gap-6">
-    <h1 class="text-4xl font-narrative text-sky-text">{{ $t('landing.title') }}</h1>
+  <div class="min-h-screen flex flex-col items-center justify-center gap-6 px-4">
+    <h1 class="text-4xl md:text-5xl font-narrative text-sky-text text-center">{{ $t('landing.title') }}</h1>
     <p class="text-xl font-ui text-sky-text/70">{{ $t('landing.subtitle') }}</p>
     <div class="flex gap-4 mt-4">
-      <button class="px-6 py-3 bg-sky-accent text-sky-dark font-ui font-semibold rounded-lg">
+      <NuxtLink
+        :to="localePath('/projets')"
+        class="px-6 py-3 bg-sky-accent text-sky-dark font-ui font-semibold rounded-lg hover:opacity-90 transition-opacity"
+      >
         {{ $t('landing.cta_adventure') }}
-      </button>
-      <button class="px-6 py-3 border border-sky-text/30 text-sky-text font-ui rounded-lg">
+      </NuxtLink>
+      <NuxtLink
+        :to="localePath('/resume')"
+        class="px-6 py-3 border border-sky-text/30 text-sky-text font-ui rounded-lg hover:border-sky-accent hover:text-sky-accent transition-colors"
+      >
         {{ $t('landing.cta_express') }}
-      </button>
+      </NuxtLink>
     </div>
   </div>
 </template>
+
+<script setup lang="ts">
+const { setPageMeta } = useSeo()
+const { t } = useI18n()
+const localePath = useLocalePath()
+
+setPageMeta({
+  title: t('meta.title'),
+  description: t('meta.description'),
+})
+</script>