Help me functionally test my app on mobile, for real, before launch. This is about whether it works, not load times. 1. Device pass: give me a checklist to walk through on an actual phone (mine, plus a borrowed one on the other platform if possible: one iOS Safari, one Android Chrome). The walk covers signup, login, the primary create/edit action, and checkout, start to finish, on the real device. 2. What to look for per flow: tap targets too small or too close together, the on-screen keyboard covering the input being typed in, wrong keyboard types (email fields should trigger the email keyboard, number fields numeric), forms that cannot be submitted because the submit button is hidden behind the keyboard, hover-dependent UI that has no touch equivalent, dropdowns and date pickers that are unusable on touch, horizontal scrolling or content wider than the viewport, and modals that cannot be closed on a small screen. 3. Mobile-specific flows: test the things that only happen on phones: pasting a verification code from an SMS/email app switch, the browser's back gesture, and what happens when a phone call interrupts checkout mid-payment. 4. Emulated coverage: add mobile viewport emulation (Playwright device profiles or equivalent) to my e2e suite for the core flows so layout regressions get caught automatically. Emulation catches layout bugs; the real device catches interaction bugs. Both matter. 5. Fix and retest: fix each issue found and confirm on the real device, not just in dev tools. Do not treat Chrome dev tools device emulation as sufficient on its own. Do not rebuild the UI for mobile; fix the specific breakages found. Give me: the device testing checklist, the emulated test additions, and a per-issue list of what was found and fixed.