feat(arcturus): add arcturus host

modules/hosts/arcturus/config.nix

@@ -0,0 +1,84 @@
+{ config, ... }:
+{
+  flake.modules.nixos.arcturus =
+    {
+      pkgs,
+      hostName,
+      userName,
+      ...
+    }:
+    {
+      imports = with config.flake.modules.nixos; [
+        boot
+        hardware
+        networking
+        virtualisation
+      ];
+
+      tnix = {
+        boot.secure-boot.enable = true;
+        boot.impermanence.enable = true;
+        networking.openssh.enable = true;
+
+        virtualisation = {
+          docker.enable = true;
+        };
+      };
+
+      sops.secrets = {
+        tux-password = {
+          sopsFile = ./secrets.yaml;
+          neededForUsers = true;
+        };
+
+        discord-token = {
+          sopsFile = ./secrets.yaml;
+        };
+
+        gemini-api-key = {
+          sopsFile = ./secrets.yaml;
+          owner = userName;
+        };
+
+        openrouter-api-key = {
+          sopsFile = ./secrets.yaml;
+          owner = userName;
+        };
+
+        opencode-go-api-key = {
+          sopsFile = ./secrets.yaml;
+          owner = userName;
+        };
+      };
+
+      # --- Boot ---
+      boot.kernelPackages = pkgs.linuxKernel.packages.linux_zen;
+
+      # --- Networking ---
+      networking = {
+        hostName = hostName;
+        networkmanager = {
+          enable = true;
+          wifi.backend = "iwd";
+        };
+        wireless.iwd = {
+          enable = true;
+          settings = {
+            Network = {
+              EnableIPv6 = true;
+            };
+            Settings = {
+              AutoConnect = true;
+            };
+          };
+        };
+        firewall.enable = false;
+      };
+
+      environment.systemPackages = with pkgs; [
+        nvtopPackages.full
+      ];
+
+      system.stateVersion = "26.05";
+    };
+}