SettingsDaemon: add system font changed signal

settings-daemon/theme/com.cutefish.Theme.xml

@@ -74,6 +74,7 @@
     <signal name="cursorSizeChanged"></signal>
     <signal name="iconThemeChanged"></signal>
     <signal name="systemFontPointSizeChanged"></signal>
+    <signal name="systemFontChanged"></signal>
 
   </interface>
 </node>

settings-daemon/theme/thememanager.cpp

@@ -163,6 +163,8 @@ void ThemeManager::setSystemFont(const QString &fontFamily)
 {
     m_settings->setValue(s_systemFontName, fontFamily);
     updateGtkFont();
+
+    emit systemFontChanged();
 }
 
 QString ThemeManager::systemFixedFont()

settings-daemon/theme/thememanager.h

@@ -28,7 +28,7 @@ class ThemeManager : public QObject
     Q_OBJECT
     Q_PROPERTY(bool isDarkMode READ isDarkMode WRITE setDarkMode NOTIFY darkModeChanged)
     Q_PROPERTY(bool darkModeDimsWallpaer READ darkModeDimsWallpaer WRITE setDarkModeDimsWallpaer NOTIFY darkModeDimsWallpaerChanged)
-    Q_PROPERTY(QString systemFont READ systemFont WRITE setSystemFont)
+    Q_PROPERTY(QString systemFont READ systemFont WRITE setSystemFont NOTIFY systemFontChanged)
     Q_PROPERTY(QString systemFixedFont READ systemFixedFont WRITE setSystemFixedFont)
     Q_PROPERTY(qreal systemFontPointSize READ systemFontPointSize WRITE setSystemFontPointSize NOTIFY systemFontPointSizeChanged)
     Q_PROPERTY(qreal devicePixelRatio READ devicePixelRatio WRITE setDevicePixelRatio)
@@ -97,6 +97,7 @@ signals:
     void cursorSizeChanged();
     void iconThemeChanged();
     void systemFontPointSizeChanged();
+    void systemFontChanged();
 
 private:
     void updateGtkFont();