List view: playlist cards with name, description, item count.
Detail view: inline-editable name/description, ordered item list
with thumbnails, duration editing, drag-to-reorder, remove.
Add-item modal: content/widget picker with search and tabs.
All user strings escaped via esc() helper for safe innerHTML.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
