steamdeck: change specilisation to niri and fix deckyloader failing

hosts/home.nix

@@ -77,7 +77,6 @@
       unzip # Zip files
       unrar # Rar files
       papirus-icon-theme
-      arc-theme
 
       # General configuration
       #keepassxc

hosts/steamdeck/default.nix

@@ -20,9 +20,11 @@
   myDesktop.virtualisation.enable = true;
   myDesktop.nitrokey.enable = true;
 
+  nixpkgs.config.permittedInsecurePackages = ["pnpm-9.15.9"];
+
   specialisation = {
-    sway.configuration = {
-      imports = [(import ../../modules/wm/sway)];
+    niri.configuration = {
+      myDesktop.windowManager = lib.mkForce "niri";
       jovian.steam.enable = lib.mkForce false;
       services.desktopManager.plasma6.enable = lib.mkForce false;
     };

modules/wm/steam/default.nix

@@ -35,9 +35,7 @@
     decky-loader.enable = true;
   };
 
-  nixpkgs.config.permittedInsecurePackages = [
-    "pnpm-9.15.9"
-  ];
+  nixpkgs.config.permittedInsecurePackages = ["pnpm-9.15.9"];
 
   hardware.graphics = {
     enable = true;