When receiving RendererCommandApplied::SetState with a current_track,
actually download the track audio and feed it to the player before
applying the playing state. Previously only called core.resume() which
did nothing since no audio was loaded.
Matches desktop's ensure_remote_track_loaded pattern from
qconnect_service.rs. Also adds >2s threshold for seek to avoid
redundant seeks from server echo.
cc
vicrodh
3df007fe9f