初始化：图形化界面骨架（文件选择、语法高亮、自动缩进、查找/替换）

mainwindow.h

@@ -0,0 +1,53 @@
+#pragma once
+
+#include <QMainWindow>
+
+class FileBrowserWidget;
+class CodeEditorWidget;
+class CompileProcessManager;
+
+class MainWindow : public QMainWindow
+{
+    Q_OBJECT
+
+public:
+    explicit MainWindow(QWidget *parent = nullptr);
+    ~MainWindow();
+
+private slots:
+    void onActionNewFile();
+    void onActionOpenFile();
+    void onActionSaveFile();
+    void onActionExit();
+
+    void onActionBuild();
+    void onActionRun();
+
+    // 后端编译结果回调
+    void onCompileFinished(const QString &stdoutText,
+                           const QString &stderrText,
+                           int exitCode);
+
+private:
+    void createActions();
+    void createMenus();
+    void setupCentralWidgets();
+    void connectSignals();
+
+private:
+    // UI 部件
+    FileBrowserWidget     *m_fileBrowser = nullptr;
+    CodeEditorWidget      *m_codeEditor  = nullptr;
+
+    // 后端模块
+    CompileProcessManager *m_compileManager = nullptr;
+
+    // 菜单动作
+    QAction *m_actNew   = nullptr;
+    QAction *m_actOpen  = nullptr;
+    QAction *m_actSave  = nullptr;
+    QAction *m_actExit  = nullptr;
+
+    QAction *m_actBuild = nullptr;
+    QAction *m_actRun   = nullptr;
+};