launcher: configure and preview DualSense lightbar color (#912)

launcher: configure and preview controller lightbar color

Add an optional lightbar color to launcher settings and pass it to the emulator with --controller-color. Preview changes on RGB gamepads, handle controller hotplug events, and restore the saved color when settings dialogs close. Release launcher preview handles when starting a game.

Co-authored-by: m66401970-eng <m66401970@gmail.com>

src/launcher/include/controllerLightbar.h

@@ -0,0 +1,29 @@
+#ifndef CONTROLLER_LIGHTBAR_H
+#define CONTROLLER_LIGHTBAR_H
+
+#include <QColor>
+#include <QHash>
+#include <QObject>
+#include <QString>
+#include <QTimer>
+
+#include <SDL3/SDL_gamepad.h>
+
+class ControllerLightbar final: public QObject {
+public:
+	explicit ControllerLightbar(QObject* parent = nullptr);
+	~ControllerLightbar() override;
+
+	void SetColor(const QString& color);
+	void Stop();
+
+private:
+	void Refresh();
+	void ApplyColor(SDL_Gamepad* gamepad) const;
+
+	QTimer                              m_timer;
+	QHash<SDL_JoystickID, SDL_Gamepad*> m_gamepads;
+	QColor                              m_color;
+};
+
+#endif // CONTROLLER_LIGHTBAR_H