T01: Frontend Foundation – Nuxt 3 + Tailwind + Design Tokens + Layout + Meta

- Nuxt 3 project with @nuxtjs/tailwindcss module
- Tailwind CSS config with A0 Dark Theme design tokens (CSS custom properties)
- AppHeader: sticky, logo, nav, phone, social icons, mobile burger menu
- AppFooter: 4-column grid (Navigation, Kontakt, Rechtliches, Social)
- HmsLogo: SVG with orange #EC6925 border
- error.vue: 404 page with Seite nicht gefunden
- robots.txt server route: Disallow: /
- Meta: noindex, nofollow, noarchive, nosnippet
- JSON-LD: LocalBusiness schema
- OpenGraph tags
- routeRules: SSR/CSR per route
- Shared components: LoadingSkeleton, EmptyState, ErrorState, LegalContentPage, SpeakerIcon
- 42 vitest tests passing
- Build: 0 errors

frontend/components/ErrorState.vue

@@ -0,0 +1,37 @@
+<template>
+  <div
+    class="flex flex-col items-center justify-center py-12 text-center"
+    role="alert"
+  >
+    <div class="w-16 h-16 mb-4 flex items-center justify-center rounded-full bg-error-bg">
+      <svg class="w-8 h-8 text-error" fill="none" stroke="currentColor" stroke-width="1.5" viewBox="0 0 24 24" aria-hidden="true">
+        <path stroke-linecap="round" stroke-linejoin="round" d="M12 9v4m0 4h.01M4.93 19h14.14c1.54 0 2.5-1.67 1.73-3L13.73 4c-.77-1.33-2.69-1.33-3.46 0L3.2 16c-.77 1.33.19 3 1.73 3z"/>
+      </svg>
+    </div>
+    <h2 class="text-lg font-bold text-text mb-2">{{ title }}</h2>
+    <p class="text-text-muted text-sm mb-6 max-w-sm">{{ message }}</p>
+    <button
+      v-if="retryText"
+      class="btn-secondary"
+      @click="$emit('retry')"
+    >
+      {{ retryText }}
+    </button>
+  </div>
+</template>
+
+<script setup lang="ts">
+withDefaults(defineProps<{
+  title?: string;
+  message?: string;
+  retryText?: string;
+}>(), {
+  title: "Ein Fehler ist aufgetreten",
+  message: "Bitte versuchen Sie es erneut.",
+  retryText: "Erneut versuchen",
+});
+
+defineEmits<{
+  retry: [];
+}>();
+</script>