Screenshots were catching the app mid-boot at ~92% with the onboarding
Preparing progress bar still visible. waitForAppReady checked for the
composer (textarea/contenteditable) with state:'visible', but Playwright
considers an element visible even when a z-1300+ fixed overlay covers it
(non-zero bounding box, not display:none).
Now waits for the composer to be attached, then polls
document.elementFromPoint at viewport center — if the topmost element is
inside a position:fixed inset:0 overlay, the app isn't ready yet.
b2be12d456