Type Alias VideoProviderRenderer

DESIGN.md §4-video — supplies the embed for a non-'html5' provider. Build into container, call onReady() once it should show (sync or async — a spinner shows until then). signal fires 'abort' once this slide is no longer wanted; a returned cleanup can't work here since setup is often async and may resolve after eviction — release everything on abort instead, checking signal.aborted before acting on a stale slide.

setPoster(url) — DESIGN.md §4.3 — shows url in place of the spinner while still waiting on onReady. Only meaningful when item.poster itself is unset: core already shows that immediately, before this renderer even runs, and silently ignores setPoster in that case (a host-supplied poster always wins). Meant for a provider-specific fallback a renderer can resolve on its own (e.g. a predictable thumbnail URL) when the host didn't supply one — entirely optional to call at all. A no-op once onReady has already fired or signal has aborted, so a slow-resolving fallback (an async fetch, say) can never replace an already-showing real embed, or paint over a slide that's moved on.