fix(nixos): deploy from source checkout

Replace target-checkout deployment with source-built closure import and activation. Allow SteamCMD game services to stay configured without auto-starting, and disable Palworld auto-start on Pikachu.

configs/nixos/modules/services/steamcmd.nix

@@ -65,6 +65,12 @@
       default = [ ];
       description = "TCP ports opened for the game service.";
     };
+
+    autoStart = lib.mkOption {
+      type = lib.types.bool;
+      default = true;
+      description = "Start the game service during normal boot.";
+    };
   };
 
   config = lib.mkMerge [
@@ -150,7 +156,7 @@
               "steamcmd-${service.serviceName}-update.service"
             ];
             wants = [ "network-online.target" ];
-            wantedBy = [ "multi-user.target" ];
+            wantedBy = lib.mkIf service.autoStart [ "multi-user.target" ];
             serviceConfig = {
               Type = "simple";
               User = user;