island: on every monitor (experiment)

window_per_monitor with the same view: every monitor shows the island,
all sharing one state (open, hover, player). measured with music on 3
monitors: 180 frames a second in total, pill 27% of a core (was 9%),
open card 58% (was 21%), gpu 1.4 / 3.0 ms per frame each; open/close
drops 7-14 of ~175 frames (was 0-1)

src/main.rs

@@ -10,5 +10,6 @@ fn main() {
     // the card's glow follows the cover art, which art::Art copies to this one path
     Palette::write().open(&art::palette_file(), 8);
 
-    App::new().font("Fira Code").ipc("island", island::command).window(island::view).run();
+    // one island on every monitor, all showing the same player and state
+    App::new().font("Fira Code").ipc("island", island::command).window_per_monitor(|_| island::view()).run();
 }