- Add custom TaskNotes simple and gradient SVG icons
- Register tasknotes-simple icon using addIcon() with SVG masking for
transparent cutouts
- Replace ribbon "Create new task" icon from 'plus' to custom TaskNotes
icon
- Add TaskNotes icon to modal headers (task creation/edit modals)
- Enhance README with centered gradient TaskNotes logo
- Add comprehensive CSS styling for modal header icons
- Icons use currentColor/accent color theming for consistency
