feat(bruddynix): add jovian gaming-mode session

Registers a Steam Deck-style gamescope session in SDDM as an opt-in
alternative to Plasma (no auto-launch). desktopSession wires the Deck
UI's switch-to-desktop button to Plasma.

Author: khaneliman

systems/x86_64-linux/bruddynix/default.nix

@@ -1,5 +1,6 @@
 {
   config,
+  inputs,
   lib,
   ...
 }:
@@ -8,6 +9,7 @@ let
 in
 {
   imports = [
+    inputs.jovian.nixosModules.default
     ./disks.nix
     ./hardware.nix
     ./network.nix
@@ -116,6 +118,13 @@ in
         NO_POINTER_VIEWPORT = "1";
       };
 
+  # Steam Deck-style Gaming Mode as an optional SDDM session (no auto-launch)
+  jovian.steam = {
+    enable = true;
+    user = "bruddy";
+    desktopSession = "plasma";
+  };
+
   nix.settings = {
     cores = 8;
     max-jobs = 8;