feat: add minimal Debian image build system with WireGuard-only networking

Add complete build infrastructure for football secure access system:
- Minimal Debian base with only IceWM and Remmina
- WireGuard-only networking with strict firewall (eth0 allows only WireGuard)
- All network traffic routed through mandatory VPN tunnel
- Secure Boot enforced for physical deployments
- Zero remote access - SSH, telnet disabled and blocked
- AppArmor, auditd, and fail2ban for security hardening

Build system generates both VM (qcow2) and physical (raw) images.
WireGuard endpoint IP and port configurable via build script variables.

Includes:
- Package list with minimal dependencies
- System hardening scripts
- WireGuard client and server configuration tools
- Comprehensive documentation (README.md, QUICKSTART.md)
- systemd services for firewall enforcement
- User environment with automatic IceWM startup

💘 Generated with Crush

Assisted-by: GLM-4.7 via Crush <crush@charm.land>

chroot-overlay/etc/systemd/system/getty@tty1.service.d/override.conf

@@ -0,0 +1,12 @@
+[Unit]
+Description=Autologin user session for IceWM
+After=systemd-user-sessions.service
+
+[Service]
+ExecStart=
+ExecStart=-/sbin/agetty --autologin user --noclear tty1 %I $TERM
+Type=idle
+Restart=always
+
+[Install]
+WantedBy=getty.target