feat: the rebuild gamemode of "Gauntlet"

scripts/ui/admin_panel.gd

@@ -250,16 +250,12 @@ func _on_tab_changed(tab_index: int) -> void:
 func _rpc(rpc_name: String, payload: Dictionary) -> Dictionary:
 	if not NakamaManager.client or not NakamaManager.session:
 		return {"error": "Not connected"}
-	var result = await NakamaManager.client.rpc_async(
-		NakamaManager.session, rpc_name, JSON.stringify(payload)
-	)
-	if result.is_exception():
-		var err: String = result.get_exception().message
+	var result = await BackendService.api_rpc_async(rpc_name, JSON.stringify(payload))
+	if result.get("success", false) == false:
+		var err: String = str(result.get("message", "Unknown error"))
 		_set_status(err, CLR_STATUS_ERR)
 		return {"error": err}
-	if result.payload:
-		return JSON.parse_string(result.payload)
-	return {}
+	return result.get("data", {})
 
 func _set_status(msg: String, color: Color = CLR_DIM) -> void:
 	status_label.text = msg