Useful for navigation decisions: installed iOS PWAs open target="_blank"
links and cross-origin navigations in an in-app browser sheet, so apps
often want to route same-origin links internally instead. Checks the
display-mode media query (standalone/fullscreen/minimal-ui) plus the
legacy iOS navigator.standalone flag. Returns false outside the
browser.
Whether the app is running as an installed PWA (home-screen launch) rather than inside a browser tab.