feat: use signal-based xdgactivationclient API

- Update to use tokenReady signal with Qt::SingleShotConnection
- Remove callback-based requestToken usage
- Follow dde-shell xdgactivation pattern

Author: 18202781743

plugins/application-tray/sniprotocolhandler.cpp

@@ -323,12 +323,13 @@ bool SniTrayProtocolHandler::eventFilter(QObject *watched, QEvent *event)
                     auto widget = static_cast<QWidget*>(parent());
                     auto *win = widget->window()->windowHandle();
                     auto sniInter = m_sniInter;
-                    activationClient->requestToken(win, QString(), [sniInter](const QString &token) {
+                    connect(activationClient, &XdgActivationClient::tokenReady, this, [sniInter](const QString &token) {
                         if (!token.isEmpty()) {
                             sniInter->ProvideXdgActivationToken(token);
                         }
                         sniInter->Activate(0, 0);
-                    });
+                    }, Qt::SingleShotConnection);
+                    activationClient->requestToken(win);
                 } else {
                     m_sniInter->Activate(0, 0);
                 }