Revert "feat(modules/system)!: rm steam"

This reverts commit dde98cb.

Author: SymphonySimper

modules/system/default.nix

@@ -15,6 +15,7 @@
     # gui
     ./browser.nix
     ./desktop.nix
+    ./steam.nix
 
     # cli + gui
     ./android.nix

modules/system/steam.nix

@@ -0,0 +1,53 @@
+{
+  config,
+  pkgs,
+  lib,
+  ...
+}:
+let
+  cfg = config.my.programs.steam;
+in
+{
+  options.my.programs.steam = {
+    enable = lib.mkEnableOption "Steam";
+  };
+
+  config = lib.mkIf cfg.enable {
+    programs = {
+      steam = {
+        enable = true;
+
+        dedicatedServer.openFirewall = true; # Open ports in the firewall for Source Dedicated Server
+        localNetworkGameTransfers.openFirewall = true; # Open ports in the firewall for Steam Local Network Game Transfers
+        remotePlay.openFirewall = true; # Open ports in the firewall for Steam Remote Play
+
+        gamescopeSession.enable = false;
+
+        extraCompatPackages = [ pkgs.proton-ge-bin ];
+      };
+
+      # `gamescope -- %command%`
+      # for mangohud `gamescope --mangoapp -- %command%`
+      # for LD_PRELOAD `LD_PRELOAD="" gamescope -- %command%`
+      gamescope = {
+        enable = true;
+        capSysNice = false;
+        args = [
+          "-f" # full screen
+          "--mouse-sensitivity 1" # increase mouse speed
+          "--force-grab-cursor"
+          "--adaptive-sync"
+        ];
+      };
+    };
+
+    environment = {
+      sessionVariables.PROTON_ENABLE_WAYLAND = 1;
+
+      systemPackages = with pkgs; [
+        # `mangohud %command%`
+        mangohud
+      ];
+    };
+  };
+}

profiles/gui/system.nix

@@ -19,6 +19,7 @@
 
     programs = {
       android.enable = true;
+      steam.enable = true;
     };
   };