This adds foundational functionality for nixos-facter hardware detection:
- lib.nix: Internal helper functions for querying facter reports
- hasCpu/hasAmdCpu/hasIntelCpu: CPU vendor detection
- collectDrivers: Extract driver_modules from hardware entries
- toZeroPaddedHex: Format USB device IDs (for fingerprint matching)
- system.nix: Auto-detect nixpkgs.hostPlatform from facter report
Automatically sets the correct platform (x86_64-linux, aarch64-linux, etc.)
based on the hardware report, reducing manual configuration.
This builds on the base infrastructure added in PR #450303 and provides
the foundation for upcoming hardware detection modules (boot, networking,
graphics, etc.).
Part of the incremental upstreaming effort from:
https://github.com/nix-community/nixos-facter-modules
