Fix live-usb networking configuration conflict

Disable networking.wireless to prevent conflict with NetworkManager.
The installation-cd-minimal base enables both, causing a build failure.

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

machines/live-usb/configuration.nix

@@ -65,6 +65,8 @@
 
   # Enable NetworkManager for easy wifi setup
   networking.networkmanager.enable = true;
+  # Disable wireless networking (conflicts with NetworkManager)
+  networking.wireless.enable = false;
   
   # Enable SSH daemon for remote access
   services.openssh = {