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

.gitignore

@@ -1,6 +1,8 @@
 node_modules/
 .pnpm-store/
 dist/
+.nuxt/
+.output/
 .env
 .env.*
 !.env.example
@@ -8,4 +10,4 @@ coverage/
 *.log
 .DS_Store
 .agents/
-skills-lock.json
+skills-lock.json