Add simple __main__.py for Hugging Face Spaces display

This just prints a message explaining that the app needs to run on
Reachy Mini. The actual app logic is in app.py:ReachyMiniHAVoiceApp.

reachy_mini_ha_voice/__main__.py

@@ -0,0 +1,28 @@
+#!/usr/bin/env python3
+"""Main entry point - for Hugging Face Spaces display only.
+
+This application is designed to run on Reachy Mini robots.
+To use it, install the app on your Reachy Mini from the dashboard.
+
+For standalone usage, this would require command-line arguments:
+  python -m reachy_mini_ha_voice --name "ReachyMini"
+"""
+
+import sys
+
+if __name__ == "__main__":
+    print("Reachy Mini Home Assistant Voice Assistant")
+    print("=" * 50)
+    print()
+    print("This application is designed to run on Reachy Mini robots.")
+    print()
+    print("To use it:")
+    print("1. Install this app on your Reachy Mini from the dashboard")
+    print("2. Enable the app in the Reachy Mini applications section")
+    print("3. The ESPHome voice assistant will start on port 6053")
+    print("4. Home Assistant will auto-discover the device")
+    print()
+    print("For more information, see:")
+    print("https://huggingface.co/spaces/djhui5710/reachy_mini_ha_voice")
+    print()
+    sys.exit(0)