- Add Light/Dark/System theme toggle with ThemeContext and CSS variables
- Sidebar fully collapsible (icons-only mode, persisted in localStorage)
- Anwendungen section collapsible with chevron toggle
- Admin "Anpassungen" page: logo upload, sidebar color picker with presets
- Backend branding endpoints (GET/POST /settings/branding) stored in Redis
- Optional custom icon upload for external links (click icon field)
- Backend favicon proxy with HTML parsing for reliable icon loading
- Dark mode CSS variables for all components
- Login page SSO button and error styles use CSS variables
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
