feat(m1): 应用骨架、传送门面板与暂存区

- CMake 构建（Qt6 + dtk2widget + LayerShellQt）
- 单实例 / --daemon / --show
- DBlur 双栏面板：传送门 + 暂存区，layer-shell 定位，不抢焦点
- 暂存区模型：文件/文字/图片、去重、JSON 持久化、文件消失清理
- 列表委托：复选框、缩略图、名称、hover 关闭按钮
- 全选 / 反选 / 删除选中
- 应用图标（多尺寸 hicolor）与 desktop 入口
- 方案更新：确认 layer-shell + 遮挡自动隐藏

src/app.cpp

@@ -0,0 +1,82 @@
+// SPDX-FileCopyrightText: 2026 GXDE OS Team
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+#include "app.h"
+
+#include "config.h"
+#include "staging/stagingmodel.h"
+#include "ui/portalpanel.h"
+
+#include <QLocalServer>
+#include <QLocalSocket>
+
+#include <unistd.h>
+
+App::App(QObject *parent)
+    : QObject(parent)
+{
+}
+
+bool App::init(bool daemon, bool forceShow)
+{
+    Config::instance()->init();
+    m_daemon = daemon;
+
+    const QString serverName = QStringLiteral("gxde-ai-see-%1").arg(getuid());
+
+    QLocalSocket probe;
+    probe.connectToServer(serverName);
+    if (probe.waitForConnected(200)) {
+        probe.write("show");
+        probe.waitForBytesWritten(200);
+        probe.disconnectFromServer();
+        return false;
+    }
+
+    QLocalServer::removeServer(serverName);
+    m_server = new QLocalServer(this);
+    m_server->listen(serverName);
+    connect(m_server, &QLocalServer::newConnection, this, [this]() {
+        while (QLocalSocket *socket = m_server->nextPendingConnection()) {
+            connect(socket, &QLocalSocket::readyRead, this, [this, socket]() {
+                if (socket->readAll().contains("show")) {
+                    showPanel();
+                }
+            });
+            connect(socket, &QLocalSocket::disconnected, socket,
+                    &QLocalSocket::deleteLater);
+        }
+    });
+
+    m_model = new StagingModel(this);
+
+    connect(m_model, &StagingModel::countChanged, this, [this]() {
+        if (!m_daemon && !m_model->isEmpty() && m_panel) {
+            m_panel->popup();
+        }
+    });
+
+    if (!daemon || forceShow || !m_model->isEmpty()) {
+        showPanel();
+    }
+
+    return true;
+}
+
+void App::ensurePanel()
+{
+    if (m_panel) {
+        return;
+    }
+
+    m_panel = new PortalPanel(m_model);
+    connect(m_panel, &PortalPanel::openChatRequested, this, []() {
+        // TODO(M4): open the AI See chat window.
+    });
+}
+
+void App::showPanel()
+{
+    ensurePanel();
+    m_panel->popup();
+}