Add offline fallback page for PWA

- Create offline.html with user-friendly offline message
- Auto-redirect when connection is restored
- Use offline.html as navigateFallback instead of root
- Include offline.html in PWA assets for precaching

This ensures users see a proper offline page when opening the app without connection, instead of a browser error.

nuxt4/nuxt.config.ts

@@ -22,7 +22,7 @@ export default defineNuxtConfig({
 
   pwa: {
     registerType: 'autoUpdate',
-    includeAssets: ['favicon.ico', 'apple-touch-icon.png', 'icon.svg'],
+    includeAssets: ['favicon.ico', 'apple-touch-icon.png', 'icon.svg', 'offline.html'],
     manifest: {
       name: 'Plantilla Nuxt + Authentik',
       short_name: 'NuxtAuth',
@@ -72,7 +72,7 @@ export default defineNuxtConfig({
       ]
     },
     workbox: {
-      navigateFallback: '/',
+      navigateFallback: '/offline.html',
       navigateFallbackDenylist: [/^\/api\//, /^\/authentik\//],
       globPatterns: ['**/*.{js,css,html,png,svg,ico,json}'],
       cleanupOutdatedCaches: true,