/** * Smoke test for the iOS/PWA fullscreen-button fix (Task #52). * * Bug: on an iPhone running the installed PWA in portrait (standalone * display-mode), tapping the fullscreen button did nothing. Root cause: iOS * Safari does not implement the standard Fullscreen API * (Element.requestFullscreen) for arbitrary elements — even in a standalone * PWA — so `stage.requestFullscreen?.()` silently no-ops. WebKit instead * exposes a video-only, non-standard fallback, * HTMLVideoElement.webkitEnterFullscreen/webkitExitFullscreen, which does * work in standalone mode. * * Playwright/Chromium implements the standard Fullscreen API, so to exercise * the WebKit fallback branch we delete `requestFullscreen` from the stage * element (simulating iOS Safari) and stub `webkitEnterFullscreen` / * `webkitExitFullscreen` on the