Redesign the skill detail panel to use a directory tree + file viewer
layout, similar to a file browser. SKILL.md and supporting files are
shown in a collapsible tree on the left; selecting a file renders its
content on the right with markdown preview (including YAML frontmatter
parsing) and an edit toggle.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
