Ensure first_time_install.sh runs in non-interactive mode by passing both:
1. The -y command-line flag
2. The LEDMATRIX_ASSUME_YES=1 environment variable
This is necessary because first_time_install.sh re-executes itself with sudo
if not running as root (line 131), and we need to ensure the non-interactive
flag is preserved through the re-execution.
Also added debug_install.sh diagnostic script to help troubleshoot
installation failures on the Pi.
