BunnyLiveStreamPlayerViewModel

Backing view model for BunnyLiveStreamPlayer. Owns the polling loop, the play-data fetches, and the trailer fetch — exposes a single StateFlow of LiveStreamPlayerState for the UI to consume. Mirrors the behaviour of Bunny's web player.

Responsibilities, in order of execution:

1. start kicks off an initial fetchPlayData (carries stream snapshot + playable URL) and, if the snapshot warrants it, an async fetchTrailerUrl. Starts the 5s poll loop.

2. The poll loop calls LiveStreamRepository.pollLiveStream every 5 s — lightweight, returns only the stream snapshot, no play-data. In-flight guard prevents overlapping requests.

3. Whenever the snapshot status transitions to a state that needs a URL we don't have yet (Running with no live URL; Ended/VodProcessing+recordVod with no VOD URL), the view model re-fetches play-data to pick up the new URL. We avoid re-fetching on every poll because play-data is the heavier endpoint.

4. Lifecycle: onForeground fires one immediate poll then resumes the 5s cadence; onBackground cancels the loop. Terminal failure (401/403/404/410) stops polling permanently per the spec.

The class deliberately does not own any Android Context, ExoPlayer, or View — those live in the composable. This keeps it unit-testable on the JVM with a fake LiveStreamRepository.