fix(overhaul): UI and resolution bugs for Steam Deck (Gamescope)

Signed-off-by: Collecting <collecting@noreply.localhost>

src/citron/util/performance_overlay.h

@@ -15,12 +15,13 @@
 #include "citron/uisettings.h"
 
 class GMainWindow;
+class QSizeGrip;
 
 class PerformanceOverlay : public QWidget {
     Q_OBJECT
 
 public:
-    explicit PerformanceOverlay(GMainWindow* parent);
+    explicit PerformanceOverlay(QWidget* parent);
     ~PerformanceOverlay() override;
 
     void SetVisible(bool visible);
@@ -51,6 +52,7 @@ private:
     void AddFrameTime(double frame_time_ms);
 
     GMainWindow* main_window;
+    QSizeGrip* size_grip;
     QTimer update_timer;
 
     // Performance data