feat(koumakyou): initial configuration

spec/koumakyou/jovian.nix

@@ -0,0 +1,28 @@
+{ jovian, ... }: {
+  jovian = {
+    hardware.has.amd.gpu = true;
+    steamos.useSteamOSConfig = true;
+
+    steam = {
+      enable = true;
+      user = "app";
+      #desktopSession
+    };
+
+    decky-loader = {
+      enable = true;
+      stateDir = "/nix/persist/decky";
+    };
+  };
+
+  users.home.persistApp.directories = [
+    ".steam" ".local/share/Steam" ".config/gamescope"
+  ];
+
+  users.users.decky.uid = 514;
+  users.groups.decky.gid = 514;
+
+  imports = [
+    jovian.nixosModules.jovian
+  ];
+}