feat: refactor xdgactivationclient to follow dde-shell pattern

- Use DObject private pattern (D_DECLARE_PRIVATE)
- Use signal-based API (tokenReady signal) instead of callback
- Create shared library for multiple plugins to use
- Follow dde-shell xdgactivation implementation pattern

Refs: https://github.com/linuxdeepin/dde-shell/blob/master/frame/wayland/xdgactivation.h

Author: 18202781743

src/tray-wayland-integration/xdgactivationclient_p.h

@@ -0,0 +1,28 @@
+// SPDX-FileCopyrightText: 2026 UnionTech Software Technology Co., Ltd.
+//
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+#pragma once
+
+#include "xdgactivationclient.h"
+
+#include <dobject_p.h>
+
+#include <QPointer>
+
+namespace tray {
+
+class XdgActivationTokenV1;
+
+class XdgActivationClientPrivate : public DTK_CORE_NAMESPACE::DObjectPrivate
+{
+public:
+    explicit XdgActivationClientPrivate(XdgActivationClient *qq);
+    ~XdgActivationClientPrivate() override;
+
+    QPointer<XdgActivationTokenV1> provider;
+
+    D_DECLARE_PUBLIC(XdgActivationClient)
+};
+
+} // namespace tray