Pull audio_preload (background fetch + analysis seed for the next
track in the queue) out of audio/commands.rs into
audio/preload_commands.rs (~67 LOC). It's a self-contained
fetch-and-cache flow — distinct from audio_chain_preload (which
constructs the gapless source chain) and audio_play (which starts
playback) so it makes sense to live alongside them rather than inside
the same file.
audio/commands.rs: 1241 → 1185 LOC. lib.rs invoke_handler updated.
Psychotoxical