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/home/user/.icewm/preferences

@@ -0,0 +1,27 @@
+# IceWM configuration for football system
+
+# Window placement
+TaskBarShowClock=1
+TaskBarShowStartMenu=1
+TaskBarShowWindowListMenu=1
+TaskBarShowWorkspaces=0
+TaskBarShowWindows=0
+
+# Auto-start Remmina
+StartupCommand="remmina"
+
+# No desktop icons (clean interface)
+DesktopBackgroundCenter=1
+DesktopBackgroundColor="rgb:00/33/66"
+
+# Security - minimize features
+ShowLoginStatus=0
+ShowLogoutMenu=1
+ShowSettingsMenu=0
+ShowHelpMenu=0
+ShowRunProgram=0
+
+# Remmina should be main focus
+ClickToFocus=1
+FocusOnAppRaise=1
+RaiseOnFocus=1