Replaces the inherited 4-editor channel-creation chain with a single
library-to-lineup builder: browse/search library with artwork, drag
shows into the lineup, friendly toggles (shuffle, always-on), one image
for logo+bug, technical settings via built-in/custom Channel Templates
with advanced override. Lists prerequisite backend gaps (composite
create endpoint, Channel Templates, library browse API, full image-type
support incl. transparent re-encode, unified logo/bug, always-on vs
on-demand) and a Claude Design prompt for the screen.
Refs #59
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>