refactor(nixos): rely on SteamCMD app metadata

configs/nixos/hosts/pikachu/default.nix

@@ -71,7 +71,6 @@
     steamDir = "/pikachu/data/steamcmd";
     serviceName = "valheim";
     appId = 896660;
-    runtimeAppId = 892970;
     installDir = "/pikachu/data/servers/valheim/main";
     stateDir = "/pikachu/media/games/servers/valheim/main";
     executable = "./valheim_server.x86_64";

configs/nixos/modules/services/steamcmd.nix

@@ -7,7 +7,6 @@
 let
   cfg = config.modules.services.steamcmd;
 
-  runtimeAppId = if cfg.runtimeAppId == null then cfg.appId else cfg.runtimeAppId;
   libraryPath = lib.concatStringsSep ":" cfg.libraryDirs;
 
   prepareScript = pkgs.writeShellScript "steamcmd-${cfg.serviceName}-prepare" ''
@@ -37,7 +36,6 @@ let
     set -eu
 
     cd ${lib.escapeShellArg cfg.installDir}
-    export SteamAppId=${lib.escapeShellArg (toString runtimeAppId)}
     ${lib.optionalString (cfg.libraryDirs != [ ]) ''export LD_LIBRARY_PATH=${lib.escapeShellArg libraryPath}:''${LD_LIBRARY_PATH-}''}
     exec ${lib.getExe pkgs.steam-run} ${lib.escapeShellArg cfg.executable} ${lib.escapeShellArgs cfg.arguments}
   '';
@@ -85,13 +83,6 @@ in
       description = "Steam app ID for the dedicated server package.";
     };
 
-    runtimeAppId = lib.mkOption {
-      type = lib.types.nullOr lib.types.ints.positive;
-      default = null;
-      example = 892970;
-      description = "Steam app ID exposed to the running server through SteamAppId. Defaults to appId.";
-    };
-
     installDir = lib.mkOption {
       type = lib.types.str;
       example = "/data/servers/valheim/main";