fix: 修复启动白屏与地图崩溃问题

- SetUseOpenGL(false): QGLWidget 在当前系统不兼容，改用软件渲染
- ExtensionHost_v2: 添加 contributionRegistry() getter 修复空指针
- main.cpp: 两阶段启动 (show → QTimer::singleShot → initialize)
- mainwindow: 分离构造函数与 initialize()，结尾调用 onTabIndexChanged(3)
- 修复 Qt DLL 部署：使用 windeployqt 确保运行时库版本匹配

App/Plugins/PluginImporter.h

@@ -0,0 +1,42 @@
+#ifndef PLUGINIMPORTER_H
+#define PLUGINIMPORTER_H
+
+#include <QObject>
+#include <QString>
+
+class ExtensionHost;
+
+class PluginImporter : public QObject
+{
+    Q_OBJECT
+public:
+    explicit PluginImporter(ExtensionHost *extHost, QObject *parent = nullptr);
+
+    enum ImportResult {
+        Success = 0,
+        InvalidPlugin,
+        FileNotFound,
+        CopyFailed,
+        AlreadyExists,
+        LoadFailed
+    };
+
+    ImportResult importFromDirectory(const QString &dirPath);
+    ImportResult importFromZip(const QString &zipPath);
+    QString lastError() const { return m_lastError; }
+
+signals:
+    void importProgress(const QString &step, int percent);
+    void importCompleted(const QString &pluginName, bool success);
+    void importError(const QString &error);
+
+private:
+    ImportResult copyPluginFiles(const QString &sourceDir, const QString &targetDir);
+    bool validatePlugin(const QString &dirPath);
+
+    ExtensionHost *m_extHost;
+    QString m_lastError;
+    QString m_pluginsDir;
+};
+
+#endif