foundryvtt: Enable backups

configuration/services/foundryvtt.nix

@@ -35,4 +35,12 @@ in {
       proxyPass = "http://localhost:${toString port}";
     };
   };
+
+  services.backups.foundryvtt = {
+    user = "foundryvtt";
+    paths = [
+      config.services.foundryvtt.dataDir
+    ];
+    pauseServices = ["foundryvtt.service"];
+  };
 }