feat: implement configurable font settings for VTK viewports and GUI elements with persistent preferences.

app/gcompose/src/PreferencesDialog.h

@@ -4,6 +4,8 @@
 #include <QDialog>
 #include <QCheckBox>
 #include <QComboBox>
+#include <QSpinBox>
+#include <QPushButton>
 #include <map>
 #include <string>
 #include "Settings.h"
@@ -23,6 +25,22 @@ private:
     QCheckBox* m_throttledRendering;
     QComboBox* m_themeCombo;
     std::map<Settings::Dimension, QComboBox*> m_unitCombos;
+
+    // Font Configuration
+    QComboBox* m_fontFamilies;
+    QSpinBox* m_fontSize;
+    QCheckBox* m_fontBold;
+    QCheckBox* m_fontItalic;
+    QPushButton* m_fontColorBtn;
+    Vector3d m_currentFontColor;
+    
+    // GUI Font Configuration
+    QComboBox* m_guiFontFamilies;
+    QSpinBox* m_guiFontSize;
+    QCheckBox* m_guiFontBold;
+    QCheckBox* m_guiFontItalic;
+
+    void updateFontColorButton();
 };
 
 } // namespace Qt