Tester, mid-gig: "the second song in the gig started when the first one ended.
But it showed the flyover intro again."
The flyover is arriving at the venue, and you arrive once. #968 stopped it
replaying on an arrangement SWITCH (same filename), but a gig's song 2 is a
genuinely different file, so it took the full-teardown path and played the
arrival flyover again — the camera flew in from the back of the room before
every track of the set.
The play queue now answers isContinuation(): false for the first song of a set
(or a standalone play — an arrival), true for song 2..N. onSongLoaded carries
the room over to the new song's loop on a continuation, and only a real arrival
plays the intro.
Verified on the built AppImage: isContinuation goes false (song 1) -> true
(song 2) across an advance, and song 2 no longer flies in.
Also confirmed NOT a bug, same session: "didn't show the author for the second
song." The credits card shows on a queue advance whenever the song carries
authors — reproduced with a song that has them as the advanced-to track. The
tester's song 2 simply had no `authors:` metadata (most auto-converted feedpaks
don't). No code change.
Tests: isContinuation across start/advance/clear, and that onSongLoaded gates the
flyover on the continuation check. Both fail on pre-fix source. JS 1214/1214.
