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>

frontend/src/components/admin/index.ts

@@ -7,4 +7,12 @@ export { AdminAuthWrapper } from './AdminAuthWrapper';
 export { PhotoUpload } from './PhotoUpload';
 export { CategoryManager } from './CategoryManager';
 export { EventCategoryManager } from './EventCategoryManager';
-export { CMSEditor } from './CMSEditor';
+export { CMSEditor } from './CMSEditor';
+export { BulkArchiveModal } from './BulkArchiveModal';
+export { MaintenanceBanner } from './MaintenanceBanner';
+export { EmailPreviewModal } from './EmailPreviewModal';
+export { AdminPhotoGrid } from './AdminPhotoGrid';
+export { AdminPhotoViewer } from './AdminPhotoViewer';
+export { PhotoFilters } from './PhotoFilters';
+export { PasswordResetModal } from './PasswordResetModal';
+export { AdminAuthenticatedImage } from './AdminAuthenticatedImage';