This adds automatic kernel module detection for boot-critical hardware:
- disk.nix: Detects and loads kernel modules for storage controllers
Auto-detects modules for: disk controllers, storage controllers,
and FireWire controllers (for FireWire-attached disks).
Modules are automatically added to boot.initrd.availableKernelModules.
- keyboard.nix: Detects USB controller drivers for keyboard support
Ensures USB HID drivers are loaded in initrd for keyboard access
during boot (critical for LUKS password entry, etc.).
Follow up to #454237.
Part of incremental upstreaming from nixos-facter-modules.
