Add internal styleguide page with HTTP Basic Auth

- Create /internal/styleguide route with protected layout
- Add styleguide.vue layout with auth protection
- Configure internal pages auth credentials in .env.example
- Update nuxt.config for internal routes handling

nuxt.config.ts

@@ -2,7 +2,9 @@
 export default defineNuxtConfig({
   compatibilityDate: '2025-01-29',
 
-  devtools: { enabled: true },
+  devtools: {
+    enabled: ['true', '1'].includes(process.env.NUXT_DEVTOOLS_ENABLED || ''),
+  },
 
   // App configuration
   app: {
@@ -36,6 +38,8 @@ export default defineNuxtConfig({
     databaseUrl: process.env.DATABASE_URL,
     redisHost: process.env.REDIS_HOST || 'localhost',
     redisPort: process.env.REDIS_PORT || '6379',
+    internalAuthUsername: process.env.INTERNAL_AUTH_USERNAME || '',
+    internalAuthPassword: process.env.INTERNAL_AUTH_PASSWORD || '',
 
     // Public (exposed to client)
     public: {