🧹 Moved almost all files to /modules. Moved some code to separate files

modules/steam.nix

@@ -0,0 +1,10 @@
+{ ... }:
+
+{
+  programs.steam = {
+   enable = true;
+   remotePlay.openFirewall = true; # Open ports in the firewall for Steam Remote Play
+   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
+  };
+}