Luraxx/pulse ? reverse-engineered prompt

Build me an iPhone app called Pulse that feels like a Whoop style readiness tracker for Fitbit Air users. It should connect to the new Google Health API, pull in sleep, heart rate, HRV, respiration, SpO2, skin temperature, and workout data, then turn that into clear daily scores for recovery, strain, sleep, and a simple biological Pulse Age. I want everything calculated on device and stored locally, with no server, no subscription, and no tracking.

Make it look polished and personal, with a Today screen, trends over time, a health monitor, and a way to customize the layout. Include a demo mode with realistic sample data so someone can try it without a Fitbit or Google account. Add a clean OAuth sign in flow, a sync log for troubleshooting, light and dark mode, and English and German support. If you need to, look up the current Google Health API docs online so the integration is correct.