- Convert HighlightsPanel buttons to use IconButton component
- Add style prop support to IconButton for custom styling
- Remove redundant CSS for old button classes (level-toggle-btn, refresh-highlights-btn, etc.)
- Keep only highlight-level-toggles container styling
- Consistent button appearance across left and right sidebars
- DRY: Single IconButton component handles all sidebar buttons
- Change default size from 44px to 33px (25% reduction)
- Update min-width and min-height in CSS to match
- Apply size reduction to toggle-sidebar-btn as well for consistency
- Add proper type guards in ContentWithResolvedProfiles to avoid type assertions
- Remove href/link functionality from IconButton component for simplification
- Replace 'as any' with proper type narrowing using type predicates