- Add MarkdownViewer, JsonViewer, SkillExplorer components with Code/Preview toggle, search (Cmd+F), TOC sidebar, and gradient fade expand/collapse
- Add FileTreeSidebar for skill file navigation (starts collapsed)
- Make file tree panel stretch to match content height
- Green download badge with icon on detail pages
- Remove Add to Stack button and sidebar collapse functionality
- Metadata displayed as clickable label pills with modal
- Add marked dependency for client-side markdown rendering
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>