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/games/palworld.nix

@@ -56,6 +56,12 @@
       description = "Advertise the server in Palworld's public lobby.";
     };
 
+    autoStart = lib.mkOption {
+      type = lib.types.bool;
+      default = true;
+      description = "Start the Palworld server during normal boot.";
+    };
+
     rcon = {
       enable = lib.mkEnableOption "Palworld RCON" // {
         default = true;
@@ -126,6 +132,7 @@
         inherit (service) steamDir installDir stateDir;
         serviceName = "palworld-${lib.toLower service.serverName}";
         appId = 2394010;
+        inherit (service) autoStart;
         executable = "${startScript}";
         arguments =
           [