feat(02-02): create AppFooter, default layout, update app.vue with useLocaleHead

- AppFooter with copyright + Gitea/LinkedIn/Fiverr social icons (rel=noopener noreferrer)
- Default layout wraps header + slot + footer with min-h-screen flex
- app.vue uses NuxtLayout + useLocaleHead for global hreflang/canonical
- Fixed a11y.github -> a11y.gitea in both locale files

app/components/layout/AppFooter.vue

@@ -0,0 +1,33 @@
+<script setup lang="ts">
+const { t } = useI18n()
+
+const socialLinks = [
+  { name: 'gitea', url: 'https://gitea.kamisama.ovh/kayjaydee', icon: 'simple-icons:gitea', ariaKey: 'a11y.gitea' },
+  { name: 'linkedin', url: 'https://linkedin.com/in/killian-dal-cin', icon: 'simple-icons:linkedin', ariaKey: 'a11y.linkedin' },
+  { name: 'fiverr', url: 'https://www.fiverr.com/users/mr_kayjaydee', icon: 'simple-icons:fiverr', ariaKey: 'a11y.fiverr' },
+]
+</script>
+
+<template>
+  <footer class="py-6 bg-gray-100 dark:bg-gray-800">
+    <div class="max-w-7xl mx-auto px-4 sm:px-6 lg:px-8 flex flex-col md:flex-row items-center justify-between gap-4">
+      <p class="text-sm text-gray-600 dark:text-gray-400">
+        {{ t('footer.copyright') }}
+      </p>
+
+      <div class="flex items-center gap-4">
+        <a
+          v-for="link in socialLinks"
+          :key="link.name"
+          :href="link.url"
+          target="_blank"
+          rel="noopener noreferrer"
+          :aria-label="t(link.ariaKey)"
+          class="min-w-11 min-h-11 inline-flex items-center justify-center rounded focus-visible:outline-none focus-visible:ring-2 focus-visible:ring-primary focus-visible:ring-offset-2 transition-colors"
+        >
+          <UIcon :name="link.icon" class="w-5 h-5 text-gray-500 dark:text-gray-400 hover:text-primary-500 transition-colors duration-150" />
+        </a>
+      </div>
+    </div>
+  </footer>
+</template>