Major config overhaul: use custom modules, setup for multi-host config, and less boilerplate

modules/system/kernel/default.nix

@@ -0,0 +1,29 @@
+{ config, lib, pkgs, ... }:
+
+let
+  cfg = config.systemSettings.cachy;
+in
+{
+  options = {
+    systemSettings.cachy = {
+      enable = lib.mkEnableOption "Enable cachyos kernel";
+      variant = lib.mkOption {
+        default = null;
+        type = lib.types.nullOr (lib.types.enum ["lto" "server" "hardened"]);
+        description = ''
+          This option determines the CachyOS kernel variant to use.
+        '';
+      };
+    };
+  };
+
+  config = lib.mkIf cfg.enable {
+    boot.kernelPackages = lib.mkMerge [
+      (lib.mkIf (cfg.variant == null) pkgs.linuxPackages_cachyos)
+      (lib.mkIf (cfg.variant == "lto") pkgs.linuxPackages_cachyos-lto)
+      (lib.mkIf (cfg.variant == "server") pkgs.linuxPackages_cachyos-server)
+      (lib.mkIf (cfg.variant == "hardened") pkgs.linuxPackages_cachyos-hardened)
+    ];
+    boot.consoleLogLevel = 0;
+  };
+}