refactor(frontend): migrate from Vite to Nuxt SPA

Replace Vite and Vue Router with Nuxt framework
Update Docker, build scripts, and env vars for Nuxt generate

frontend/pages/event-habitats/index.vue

@@ -0,0 +1,12 @@
+<script setup lang="ts">
+import HabitatList from '../../src/views/HabitatList.vue';
+
+definePageMeta({
+  name: 'event-habitat-list',
+  seo: { titleKey: 'pages.eventHabitats.title', descriptionKey: 'pages.eventHabitats.subtitle', canonicalPath: '/event-habitats' }
+});
+</script>
+
+<template>
+  <HabitatList :event-only="true" />
+</template>