steam: use wrapped package as system steam

hosts/common/programs/steam.nix

@@ -9,6 +9,7 @@
   # steam requires system-level config for e.g. firewall or controller support
   programs.steam = lib.mkIf config.sane.programs.steam.enabled {
     enable = true;
+    package = config.sane.programs.steam.package;
     # not sure if needed: stole this whole snippet from the wiki
     remotePlay.openFirewall = true; # Open ports in the firewall for Steam Remote Play
     dedicatedServer.openFirewall = true; # Open ports in the firewall for Source Dedicated Server