Editor shows scheduled product-news posts as a markdown modal: max one
per day, oldest first, each post only ever once (marked seen at
delivery). OSS default source proxies velxio.dev's public feed through
the local backend (cached ~6h, anonymous, VELXIO_NEWS=off to disable)
with seen-state in localStorage; a pro overlay can register a
server-backed per-user source via lib/newsSource.ts.