desktop-jovian: unify steam/jovian config across yarn + patiodeck

- modules/desktop-jovian.nix: shared Jovian deck-mode config (unfree
  predicate, jovian.steam, sddm, gamescope override, imports
  desktop-steam-update.nix)
- home/progs/steam-shortcuts.nix: declarative non-Steam shortcuts
  (Prism Launcher); add new entries here for all Jovian hosts
- hosts/yarn/default.nix: reduced to host-specific config only
- hosts/patiodeck/default.nix: same

hosts/patiodeck/default.nix

@@ -1,6 +1,4 @@
 {
-  pkgs,
-  lib,
   username,
   inputs,
   site_config,
@@ -9,12 +7,11 @@
 {
   imports = [
     ../../modules/desktop-common.nix
-    ../../modules/desktop-steam-update.nix
+    ../../modules/desktop-jovian.nix
     ./disk.nix
     ./impermanence.nix
 
     inputs.impermanence.nixosModules.impermanence
-    inputs.jovian-nixos.nixosModules.default
   ];
 
   networking.hostId = "a1b2c3d4";
@@ -37,30 +34,5 @@
     site_config.ssh_keys.laptop
   ];
 
-  nixpkgs.config.allowUnfreePredicate =
-    pkg:
-    builtins.elem (lib.getName pkg) [
-      "steamdeck-hw-theme"
-      "steam-jupiter-unwrapped"
-      "steam"
-      "steam-original"
-      "steam-unwrapped"
-      "steam-run"
-    ];
-
-  jovian = {
-    devices.steamdeck.enable = true;
-    steam = {
-      enable = true;
-      autoStart = true;
-      desktopSession = "niri";
-      user = username;
-    };
-  };
-
-  # Jovian-NixOS requires sddm
-  services.displayManager.sddm.wayland.enable = true;
-
-  # disable gamescope from desktop-common.nix to avoid conflict with jovian
-  programs.gamescope.enable = lib.mkForce false;
+  jovian.devices.steamdeck.enable = true;
 }