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/package.json

@@ -5,16 +5,15 @@
   "packageManager": "pnpm@10.33.2",
   "type": "module",
   "scripts": {
-    "dev": "vite --host 0.0.0.0 --port 20015",
-    "build": "vue-tsc --noEmit && vite build",
-    "lint": "vue-tsc --noEmit",
-    "typecheck": "vue-tsc --noEmit",
+    "dev": "nuxt dev --host 0.0.0.0 --port 20015",
+    "build": "nuxt generate",
+    "lint": "nuxt typecheck",
+    "typecheck": "nuxt typecheck",
     "test": "vitest run"
   },
   "dependencies": {
     "@iconify/vue": "5.0.0",
-    "@vitejs/plugin-vue": "6.0.6",
-    "vite": "8.0.10",
+    "nuxt": "4.4.4",
     "vue": "3.5.33",
     "vue-i18n": "11.4.0",
     "vue-router": "5.0.6"
@@ -22,6 +21,7 @@
   "devDependencies": {
     "@types/node": "25.6.0",
     "@vue/tsconfig": "0.9.1",
+    "postcss": "8.5.13",
     "typescript": "6.0.3",
     "vitest": "4.1.5",
     "vue-tsc": "3.2.7"