Add README screenshot

README.md

@@ -4,6 +4,12 @@
 
 The project is built for people who want the feel of a polished health app without sending their personal health archive to a third-party dashboard.
 
+## Screenshots
+
+<p align="center">
+  <img src="docs/screenshots/overview.png" alt="VYTA overview dashboard" width="360" />
+</p>
+
 ## What It Does
 
 - **VYTA Age**: a dynamic healthspan-style score based on VO2max, resting heart rate, HRV, sleep, steps and training signals.
@@ -181,3 +187,5 @@ python sync.py
 ## Status
 
 VYTA is a personal, self-hosted health app. It is not a medical device and does not provide clinical advice.
+
+