screens-playout.jsx + styles-playout.css: program monitor (HLS preview from
the sidecar), media bin, drag-drop playlist editor, transport controls. Plain
HTML5 drag-drop, no extra library. Talks to /api/v1/playout via
ZAMPP_API.fetch.
Wired into the shell: "Playout" under Operations, breadcrumb mapping, route
case in app.jsx, stylesheet + dist/screens-playout.js script in index.html.
Format dropdown defaults to 1080p5994 (matches the new channel default).
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