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/package.json

@@ -14,6 +14,7 @@
     "@tiptap/extension-link": "^2.25.0",
     "@tiptap/react": "^2.25.0",
     "@tiptap/starter-kit": "^2.25.0",
+    "@types/react-google-recaptcha": "^2.1.9",
     "axios": "^1.3.2",
     "clsx": "^2.0.0",
     "date-fns": "^2.29.3",
@@ -25,6 +26,7 @@
     "react": "^18.3.1",
     "react-countdown": "^2.3.5",
     "react-dom": "^18.3.1",
+    "react-google-recaptcha": "^3.1.0",
     "react-i18next": "^15.6.0",
     "react-image-gallery": "^1.2.11",
     "react-intersection-observer": "^9.4.3",