feat(pikachu): add initial NixOS host

hosts/pikachu/default.nix

@@ -0,0 +1,58 @@
+{
+  config,
+  pkgs,
+  ...
+}:
+# pikachu — AZW ME Pro server.
+# Disk layout is in ./disk.nix.
+# `fileSystems` for the root disk are derived from it.
+{
+  imports = [
+    ./hardware-configuration.nix
+    ./disk.nix
+  ];
+
+  system.stateVersion = "26.05";
+
+  boot.loader.systemd-boot.enable = true;
+  boot.loader.efi.canTouchEfiVariables = true;
+
+  hardware.cpu.intel.updateMicrocode = true;
+  hardware.enableRedistributableFirmware = true;
+
+  zramSwap.enable = true;
+
+  systemd.network = {
+    enable = true;
+    networks."10-uplink" = {
+      matchConfig.MACAddress = "78:55:36:07:af:49";
+      networkConfig.DHCP = "yes";
+      linkConfig.RequiredForOnline = "routable";
+    };
+  };
+  networking.useDHCP = false;
+
+  boot.zfs.forceImportRoot = false;
+
+  modules.zfs = {
+    enable = true;
+    hostId = "2346edbd";
+    pools.pikachu = { };
+  };
+
+  modules.ssh.enable = true;
+  modules.ssh.hostKeys.restore = false;
+  modules.ssh.authorizedKeys = config.modules.ssh.workstationKeys;
+
+  modules.git.enable = true;
+  modules.toolkit.enable = true;
+
+  environment.systemPackages = with pkgs; [
+    pciutils
+    smartmontools
+    usbutils
+  ];
+
+  time.timeZone = "America/New_York";
+  i18n.defaultLocale = "en_GB.UTF-8";
+}