Fix language setting not being saved to database on admin settings page

- Added default_language field to general settings state in SettingsPage
- Replaced LanguageSelector component with simple select dropdown on settings page
- Fixed public settings endpoint to read general_default_language from database
- Language setting now properly saved when clicking Save Settings button
- Setting is correctly used by gallery login page and legal pages

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

frontend/src/pages/admin/SettingsPage.tsx

@@ -4,17 +4,21 @@ import {
   Database,
   Globe,
   Key,
-  AlertCircle
+  AlertCircle,
+  Image
 } from 'lucide-react';
 import { toast } from 'react-toastify';
 
 import { Button, Card, Input, Loading } from '../../components/common';
+import { CategoryManager } from '../../components/admin/CategoryManager';
 import { useQuery, useMutation, useQueryClient } from '@tanstack/react-query';
 import { settingsService } from '../../services/settings.service';
+import { useTranslation } from 'react-i18next';
 
 export const SettingsPage: React.FC = () => {
-  const [activeTab, setActiveTab] = useState<'general' | 'storage' | 'security'>('general');
+  const [activeTab, setActiveTab] = useState<'general' | 'storage' | 'security' | 'categories'>('general');
   const queryClient = useQueryClient();
+  const { t } = useTranslation();
 
   // Fetch settings
   const { data: settings, isLoading } = useQuery({
@@ -38,7 +42,8 @@ export const SettingsPage: React.FC = () => {
     enable_watermark: false,
     enable_analytics: true,
     enable_registration: false,
-    maintenance_mode: false
+    maintenance_mode: false,
+    default_language: 'en'
   });
 
   // Security settings state
@@ -64,7 +69,8 @@ export const SettingsPage: React.FC = () => {
         enable_watermark: settings.general_enable_watermark || false,
         enable_analytics: settings.general_enable_analytics || true,
         enable_registration: settings.general_enable_registration || false,
-        maintenance_mode: settings.general_maintenance_mode || false
+        maintenance_mode: settings.general_maintenance_mode || false,
+        default_language: settings.general_default_language || 'en'
       });
 
       // Extract security settings
@@ -166,6 +172,16 @@ export const SettingsPage: React.FC = () => {
           >
             Security
           </button>
+          <button
+            onClick={() => setActiveTab('categories')}
+            className={`py-2 px-1 border-b-2 font-medium text-sm transition-colors ${
+              activeTab === 'categories'
+                ? 'border-primary-600 text-primary-600'
+                : 'border-transparent text-neutral-500 hover:text-neutral-700'
+            }`}
+          >
+            Categories
+          </button>
         </nav>
       </div>
 
@@ -280,6 +296,29 @@ export const SettingsPage: React.FC = () => {
                 <span className="ml-2 text-sm text-neutral-700">Enable maintenance mode</span>
               </label>
             </div>
+          </Card>
+
+          <Card padding="md">
+            <h2 className="text-lg font-semibold text-neutral-900 mb-4">{t('settings.general.language')}</h2>
+            
+            <div className="space-y-4">
+              <div>
+                <label className="block text-sm font-medium text-neutral-700 mb-2">
+                  {t('settings.general.language')}
+                </label>
+                <select
+                  value={generalSettings.default_language}
+                  onChange={(e) => setGeneralSettings(prev => ({ ...prev, default_language: e.target.value }))}
+                  className="w-full px-3 py-2 border border-neutral-300 rounded-lg focus:outline-none focus:ring-2 focus:ring-primary-500 focus:border-primary-500"
+                >
+                  <option value="en">English</option>
+                  <option value="de">Deutsch</option>
+                </select>
+                <p className="text-xs text-neutral-500 mt-1">
+                  Sets the default language for all gallery pages and login screens
+                </p>
+              </div>
+            </div>
 
             <div className="mt-6">
               <Button
@@ -288,7 +327,7 @@ export const SettingsPage: React.FC = () => {
                 isLoading={saveGeneralMutation.isPending}
                 leftIcon={<Save className="w-5 h-5" />}
               >
-                Save General Settings
+                {t('settings.general.saveSettings')}
               </Button>
             </div>
           </Card>
@@ -510,6 +549,29 @@ export const SettingsPage: React.FC = () => {
           </Card>
         </div>
       )}
+
+      {/* Categories Tab */}
+      {activeTab === 'categories' && (
+        <div className="space-y-6">
+          <Card padding="md">
+            <CategoryManager />
+          </Card>
+          
+          <Card padding="md">
+            <div className="flex items-start gap-3">
+              <Image className="w-5 h-5 text-blue-600 flex-shrink-0" />
+              <div>
+                <h3 className="text-sm font-semibold text-blue-900">About Photo Categories</h3>
+                <p className="text-sm text-blue-700 mt-1">
+                  Global categories are available for all events. You can also create event-specific 
+                  categories when editing individual events. Categories help organize photos and 
+                  allow guests to filter photos by type in the gallery view.
+                </p>
+              </div>
+            </div>
+          </Card>
+        </div>
+      )}
     </div>
   );
 };