Use less pointers in frontend

src/frontend/CodeModel.hpp

@@ -0,0 +1,12 @@
+#pragma once
+#include <QAbstractTableModel>
+
+class CodeModel final : public QAbstractTableModel {
+  Q_OBJECT
+public:
+  ~CodeModel() override {}
+  explicit CodeModel(QObject *parent = nullptr) {}
+  int rowCount(const QModelIndex &parent = QModelIndex()) const override { return 1; }
+  int columnCount(const QModelIndex &parent = QModelIndex()) const override { return 2; }
+  QVariant data(const QModelIndex &index, int role = Qt::DisplayRole) const override { return {}; }
+};