feat: update specification with pre-flight discussion decisions

- Update compliance: CMMC Level 3, LI-SaaS, CIS+STIG, adapt Debian 11 STIG
- Add QR code import capability with zbar and desktop shortcut
- Add package management disabling hook with chattr +i
- Update preseed: US/Chicago timezone, US keyboard, password complexity
- Add secure boot: UEFI only, measured boot, custom keys
- Add .gitignore to exclude ISO files
- Remove package management from applications, add test suite
- Add minimal package list (no aptitude/synaptic)
- Update testing: in-ISO tests, command line execution

.gitignore

@@ -0,0 +1,43 @@
+# .gitignore for Secure Debian ISO Project
+
+# Output directory
+output/
+
+# Generated ISO files
+*.iso
+*.iso.sha256
+*.iso.asc
+
+# Build artifacts
+config/binary
+config/cache
+config/chroot
+config/.build
+
+# Live-build temporary files
+binary-hybrid.iso
+live-build.log
+
+# Virtual machine images
+*.qcow2
+*.vmdk
+*.img
+
+# Test artifacts
+test-reports/
+coverage/
+
+# IDE and editor files
+.vscode/
+.idea/
+*.swp
+*.swo
+*~
+
+# OS specific files
+.DS_Store
+Thumbs.db
+
+# Temporary files
+tmp/
+temp/