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/gallery/GalleryLayout.tsx

@@ -3,7 +3,7 @@ import { Link } from 'react-router-dom';
 import { Calendar, Clock, Download, LogOut } from 'lucide-react';
 import { format, parseISO } from 'date-fns';
 import { useTranslation } from 'react-i18next';
-import { Button, LanguageSelector } from '../common';
+import { Button } from '../common';
 import { DynamicFavicon } from '../common/DynamicFavicon';
 
 interface GalleryLayoutProps {
@@ -56,7 +56,7 @@ export const GalleryLayout: React.FC<GalleryLayoutProps> = ({
               {brandingSettings?.logo_url && (
                 <div className="pr-4 border-r border-neutral-200">
                   <img 
-                    src={brandingSettings.logo_url} 
+                    src={`${import.meta.env.VITE_API_URL || 'http://localhost:3001'}${brandingSettings.logo_url}`} 
                     alt={brandingSettings.company_name || 'Company Logo'}
                     className="h-12 w-auto object-contain"
                   />
@@ -94,7 +94,6 @@ export const GalleryLayout: React.FC<GalleryLayoutProps> = ({
             
             <div className="flex items-center gap-2">
               {headerExtra}
-              <LanguageSelector />
               {showDownloadAll && onDownloadAll && (
                 <Button
                   variant="primary"

frontend/src/components/gallery/GalleryView.tsx

@@ -231,14 +231,6 @@ export const GalleryView: React.FC<GalleryViewProps> = ({ slug, event }) => {
         <ExpirationBanner daysRemaining={daysUntilExpiration} expiresAt={event.expires_at} />
       )}
 
-      {/* Welcome Message */}
-      {event.welcome_message && (
-        <div className="mt-6">
-          <div className="bg-primary-50 border border-primary-200 rounded-lg p-4">
-            <p className="text-primary-900">{event.welcome_message}</p>
-          </div>
-        </div>
-      )}
 
       {/* Search and Filters */}
       <div className="mt-6">