feat(01-01): initialize Nuxt 4 project with all modules

- nuxt.config.ts with compatibilityVersion 4, SSR, 6 modules
- app/app.vue and app/pages/index.vue minimal setup
- pnpm as package manager with all dependencies installed
- TypeScript strict mode enabled
- .gitignore updated for Nuxt (.nuxt, .output, .env)
- tsconfig.json extends .nuxt/tsconfig.json

.gitignore

@@ -28,4 +28,9 @@ coverage
 *.sw?
 
 *.tsbuildinfo
-.claude
+.claude
+
+# Nuxt
+.nuxt
+.output
+.env