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/contexts/GalleryAuthContext.tsx

@@ -16,7 +16,7 @@ interface GalleryEvent {
 interface GalleryAuthContextType {
   isAuthenticated: boolean;
   event: GalleryEvent | null;
-  login: (slug: string, password: string) => Promise<void>;
+  login: (slug: string, password: string, recaptchaToken?: string | null) => Promise<void>;
   logout: () => void;
   isLoading: boolean;
   error: string | null;
@@ -62,11 +62,11 @@ export const GalleryAuthProvider: React.FC<GalleryAuthProviderProps> = ({ childr
     setIsLoading(false);
   }, []);
 
-  const login = async (slug: string, password: string) => {
+  const login = async (slug: string, password: string, recaptchaToken?: string | null) => {
     try {
       setError(null);
       setIsLoading(true);
-      const response = await authService.verifyGalleryPassword(slug, password);
+      const response = await authService.verifyGalleryPassword(slug, password, recaptchaToken);
       setEvent(response.event);
       setIsAuthenticated(true);