Implement safe, non-conflicting loopback boot method with BOOT button exit and automatic 120s timeout reset

main.py

@@ -69,6 +69,17 @@ led_modes = [
 local_led_mode_idx = 1 # Green breathing
 
 def main():
+    # Check if we should run the audio loopback test instead
+    import os
+    try:
+        os.stat("run_loopback.txt")
+        print("run_loopback.txt found! Starting local audio loopback test...")
+        import demo_audio_loopback
+        demo_audio_loopback.main()
+        return
+    except OSError:
+        pass
+
     global local_led_mode_idx
     import board_config