Core: support configuring window before it opens

Signed-off-by: Stephen Gutekanst <stephen@hexops.com>

examples/play-opus/App.zig

@@ -37,6 +37,7 @@ fn init(
     audio: *mach.Audio.Mod,
     app: *Mod,
 ) !void {
+    core.schedule(.init);
     audio.schedule(.init);
     app.schedule(.after_init);