Initial project scaffold for Setec Partition Wizard

C++17/Qt6 application for disk recovery, repair, flashing, formatting,
and USB security key creation on Windows. Includes CMake build system,
tabbed UI shell with 6 main tabs, core type system with Result<T>
monadic error handling, admin elevation, and dark Catppuccin theme.

src/ui/MainWindow.h

@@ -0,0 +1,51 @@
+#pragma once
+
+#include <QMainWindow>
+
+class QTabWidget;
+class QMenuBar;
+class QToolBar;
+class QStatusBar;
+
+namespace spw
+{
+
+class DiskPartitionTab;
+class RecoveryTab;
+class ImagingTab;
+class DiagnosticsTab;
+class SecurityTab;
+class MaintenanceTab;
+
+class MainWindow : public QMainWindow
+{
+    Q_OBJECT
+
+public:
+    explicit MainWindow(QWidget* parent = nullptr);
+    ~MainWindow() override;
+
+private:
+    void setupMenuBar();
+    void setupToolBar();
+    void setupTabs();
+    void setupStatusBar();
+
+private slots:
+    void onAbout();
+    void onRefreshDisks();
+
+private:
+    QTabWidget* m_tabWidget = nullptr;
+    QToolBar* m_toolBar = nullptr;
+
+    // Tabs
+    DiskPartitionTab* m_diskPartitionTab = nullptr;
+    RecoveryTab* m_recoveryTab = nullptr;
+    ImagingTab* m_imagingTab = nullptr;
+    DiagnosticsTab* m_diagnosticsTab = nullptr;
+    SecurityTab* m_securityTab = nullptr;
+    MaintenanceTab* m_maintenanceTab = nullptr;
+};
+
+} // namespace spw