v0.1.0-alpha.6

Changes since alpha.5

• Fix: corrected the is_playing detection query. historySongs.historySinger is an integer FK into a separate historySingers table (not the singer name directly), and the song identifier in history is a text disc ID rather than the integer dbSongs.songid. The join now follows the correct chain: historySingers(name→id) → historySongs(filepath) → dbSongs(path→songid) → queueSongs.