Features added:
- Leftover media management page in admin panel with delete functionality for images and videos
- Individual file delete buttons for leftover media
- PDF to PNG conversion (each page becomes a separate image at Full HD resolution)
- Delete functionality for leftover video files
- Enhanced playlist management with duration editing for all content types
- Improved dark mode support for playlist management page
- Content type badges with color coding
- Better styling for duration input fields with save functionality
- Fixed URL generation for duration update endpoint
- Created 10 SVG icon files in app/static/icons/ (Feather Icons style)
- Updated base.html with SVG icons in navigation and dark mode toggle
- Updated dashboard.html with icons in stats cards and quick actions
- Updated content_list_new.html (playlist management) with SVG icons
- Updated upload_media.html with upload-related icons
- Updated manage_player.html with player management icons
- Icons use currentColor for automatic theme adaptation
- Removed emoji dependency for better Raspberry Pi compatibility
- Added ICON_INTEGRATION.md documentation
