Add /boot partition expansion plan and temporary configurationLimit fix

- Add comprehensive BOOT_EXPANSION_PLAN.md with step-by-step instructions for safely expanding /boot from 100MB to 1GB
- Temporarily reduce configurationLimit to 1 to resolve immediate /boot space crisis
- Plan supports 20 generations (configurationLimit = 20) after expansion
- Uses safe approach: shrink /games partition, create new EFI partition
- Includes full recovery context and troubleshooting information

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

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

machines/zix790prors/configuration.nix

@@ -34,7 +34,7 @@ with lib;
 
   # Use the systemd-boot EFI boot loader.
   boot.loader.systemd-boot.enable = true;
-  boot.loader.systemd-boot.configurationLimit = 2; # Reduced to save /boot space (TODO Increase /boot partition size)
+  boot.loader.systemd-boot.configurationLimit = 1; # Temporarily reduced to 1 to free /boot space
   boot.loader.efi.canTouchEfiVariables = true;
   boot.loader.timeout = 10;