chore: fix await in cleanup script (backport: 3-0-x). #14696

docs: specify BrowserWindow features passable to window.open. #14702

Fix second-instance handler signature. #14748

fix: do not set layer explicitly for frameless window. #14736

fix: actually return appmetrics. #14750

fix: initialize tracing controller before starting platform (3-0-x). #14503

docs: clarify allowable background colors for BrowserWindow transparency (backport: 3-0-x). #14781

fix: inconsistent titleBarStyle on transparent fullscreen. #14790

chore: bump libcc (3-0-x). #14809

fix: get background color from GtkMenuBar#menubar. #14812