Add architecture to README

README.md

@@ -4,6 +4,14 @@ Conversational demo for the Reachy Mini robot combining OpenAI's realtime APIs,
 
 ![Reachy Mini Dance](src/reachy_mini_conversation_demo/images/reachy_mini_dance.gif)
 
+## Architecture
+
+The demo follows a layered architecture connecting the user, AI services, and robot hardware:
+
+<p align="center">
+  <img src="src/reachy_mini_conversation_demo/images/conversation_demo_arch.svg" alt="Architecture Diagram" width="600"/>
+</p>
+
 ## Overview
 - Real-time audio conversation loop powered by the OpenAI realtime API and `fastrtc` for low-latency streaming.
 - Vision processing uses gpt-realtime by default (when camera tool is used), with optional local vision processing using SmolVLM2 model running on-device (CPU/GPU/MPS) via `--local-vision` flag.