_broadcastState only set updatePosition on transitions, so the lock-
screen / Wear / Android Auto scrubber jumped in chunks (the in-app bar
uses positionStream and was fine). Add _positionBroadcastTimer: a 1s
periodic PlaybackState re-broadcast while actively playing so
updateTime/updatePosition stay fresh and external surfaces interpolate
smoothly. Idempotent (driven from _broadcastState, which the tick
itself calls — guarded against pile-up), cancelled when not playing
and in stop(). 6a: the notification progress bar now advances since
MediaItem.duration was already set.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
bvandeusen
77a4a55522