refactor(plugins): restructure admin and message_gateway into standard layered sub-packages

backend/plugins/domain/admin/service/restart_windows.go

@@ -0,0 +1,16 @@
+//go:build windows
+
+// Copyright 2026 Arctel.net
+// SPDX-License-Identifier: Apache-2.0
+
+package service
+
+import (
+	"Wavelet/plugins/domain/admin/errs"
+	"errors"
+)
+
+// ReplaceAndRestart is blocked on Windows.
+func ReplaceAndRestart(_, _ string) error {
+	return errors.New(errs.ErrAutomaticUpgradeBlocked)
+}