docs: make the safety disclaimer explicit (not a mobility aid)

README.md

@@ -75,8 +75,8 @@ Iris is more than one model call. It orchestrates four tools and runs a control
 - **A live loop** that perceives (camera + detector), decides whether something new is worth saying, acts (calls the vision model and speaks), and remembers what it already said so it doesn't repeat.
 
 ## Safety
-Iris describes surroundings and reads text. Don't use it to get around or avoid
-obstacles. It can't judge distance reliably and isn't safe to walk by.
+Iris describes surroundings and reads text. **It is not a mobility aid.** Don't use it
+to get around or avoid obstacles. It can't judge distance reliably and isn't safe to walk by.
 
 ## Run locally
 ```bash