Add Drop impl to PlaybackEngine so the ALSA Direct writer thread is
properly stopped when the engine is dropped (e.g. streaming timeout).
Previously, a failed streaming attempt would orphan the writer thread,
keeping the ALSA device locked and blocking all subsequent playback.
Also force HTTP/1.1 for audio downloads and add detailed error chain
logging to diagnose persistent "error decoding response body" failures
for specific tracks.
vicrodh
d02090f30d