itwaasyou/Medisense ? reverse-engineered prompt

Build me a smart health monitoring web app where patients and doctors have separate views after logging in. I want a simple signup and login flow using Firebase, including the option to sign in with a username instead of email. Patients should see a dashboard with live health data like heart rate, SpO2, and temperature, with clear color coded warning states and a live chart that updates over time. Doctors should have their own dashboard where they can see upcoming appointments, a list of patients, and basic stats, plus a simple chat screen for messaging.

Make it feel modern and easy to use, with a clean responsive layout. Use simulated vitals for now so the app works without real hardware, but structure it so real IoT data could be connected later. If you need anything from current docs, look it up online and keep the build practical and polished.