feat(nixos): migrate system configuration

configs/nixos/modules/host.nix

@@ -0,0 +1,42 @@
+{
+  config,
+  lib,
+  ...
+}:
+let
+  cfg = config.modules.host;
+  user = config.user;
+  passwordSecret = "${user.name}-password";
+in
+{
+  options.modules.host.enable = lib.mkEnableOption "physical-host base configuration";
+
+  config = lib.mkIf cfg.enable {
+    nix.settings.extra-substituters = [ "https://nyx-cache.chaotic.cx/" ];
+    nix.settings.extra-trusted-public-keys = [
+      "nyx-cache.chaotic.cx:dJxTrgMC3V3cFfyIiBQDQorG6k1LsqurH/srpMSq7qk="
+    ];
+
+    nix.gc.automatic = true;
+    nix.gc.dates = "Mon 03:15";
+    nix.gc.options = "--delete-older-than 30d";
+
+    nix.optimise.automatic = true;
+    nix.optimise.dates = [ "Thu 03:45" ];
+
+    boot.loader.systemd-boot.configurationLimit = 15;
+
+    services.xserver.xkb.layout = "us";
+    services.xserver.xkb.options = "caps:escape_shifted_capslock";
+    console.useXkbConfig = true;
+
+    sops.defaultSopsFile = ../secrets/shared.yaml;
+    sops.age.keyFile = "/var/lib/sops-nix/key.txt";
+    sops.age.sshKeyPaths = [ ];
+    sops.gnupg.sshKeyPaths = [ ];
+
+    users.mutableUsers = false;
+    sops.secrets.${passwordSecret}.neededForUsers = true;
+    users.users.${user.name}.hashedPasswordFile = config.sops.secrets.${passwordSecret}.path;
+  };
+}