starsector: init and compatability fix

modules/nixos/apps/starsector/default.nix

@@ -0,0 +1,23 @@
+{
+  config,
+  lib,
+  namespace,
+  options,
+  pkgs,
+  ...
+}:
+let
+  inherit (lib) mkIf mkEnableOption;
+  cfg = config.${namespace}.apps.starsector;
+in
+{
+  options.${namespace}.apps.starsector = {
+    enable = mkEnableOption "Whether or not to enable the game starsector.";
+  };
+
+  config = mkIf cfg.enable {
+    environment.systemPackages = with pkgs; [
+      starsector
+    ];
+  };
+}