Android PiP could go silent two ways (HAB-836): the background guard read
the stale 150ms-polled isPipEnabled at the paused/hidden transition and
could pause an active PiP session, and audio focus was abandoned the
instant isPlaying flipped false. The guard now confirms PiP via the new
ground-truth getPictureInPictureStatus() (and re-checks playback state
after the await), the Android PiP poll fires its first check at t=0, and
a plain pause defers the focus abandon by a 30s grace period (cancelled
on resume; stop/end/dispose abandon immediately).

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01DxVHwbqWBb1w27u2Sb1iB5