fix: Add Livewire config and custom 404 page for subdirectory support

- Add config/livewire.php with app_url and asset_url settings
- Add custom 404 error page with consistent design
- Add error translations for all 8 languages

For subdirectory deployment:
1. Set APP_URL to include subdirectory (e.g., https://example.com/kb)
2. Set ASSET_URL if using CDN
3. Clear config cache after deployment

src/lang/fr/messages.php

@@ -115,6 +115,14 @@
         'already_registered' => 'Déjà inscrit ?',
     ],
 
+    // Errors
+    'errors' => [
+        '404_title' => 'Page non trouvée',
+        'page_not_found' => 'Page non trouvée',
+        'page_not_found_description' => 'La page que vous recherchez est introuvable.',
+        'back_to_home' => 'Retour à l\'accueil',
+    ],
+
     // Profile
     'profile' => [
         'title' => 'Profil',