Fix brand theme application and add comprehensive translations

- Fixed theme not being reflected on gallery and admin login pages
- Created GlobalThemeProvider to apply themes globally
- Updated gallery and admin login pages to use dynamic CSS variables
- Added complete translations for all admin sections in English and German:
  - Notifications management
  - Event view and creation
  - Photo upload functionality
  - Category management
  - Archive page view
  - Analytics dashboard
  - Branding and theme settings
  - System settings
  - CMS page management
  - Email configuration
- Fixed admin photo management display issues
- Fixed photo upload category assignment
- Added password reset functionality for galleries
- Improved error handling and user feedback

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

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

backend/src/routes/adminSettings.js

@@ -5,6 +5,7 @@ const fs = require('fs').promises;
 const { body, validationResult } = require('express-validator');
 const { db, logActivity } = require('../database/db');
 const { adminAuth } = require('../middleware/auth');
+const { clearMaintenanceCache } = require('../middleware/maintenance');
 const router = express.Router();
 
 // Configure multer for logo uploads
@@ -357,6 +358,11 @@ router.put('/general', adminAuth, async (req, res) => {
           updated_at: new Date()
         });
     }
+    
+    // Clear maintenance mode cache if it was updated
+    if ('general_maintenance_mode' in settings) {
+      clearMaintenanceCache();
+    }
 
     // Log activity
     await db('activity_logs').insert({