feat: Enhance Emulator and Rendering Performance with New Features

- Implemented a Cleanup method in the Emulator class to manage resources effectively during shutdown.
- Added auto-pause functionality to the emulator when the window loses focus, optimizing CPU and battery usage.
- Updated the DoRender method in the Controller class to include frame timing management and a gentle frame rate cap.
- Enhanced texture processing in the Arena class to batch process up to 8 texture commands per frame, improving rendering efficiency.

src/app/emu/emulator.h

@@ -40,9 +40,10 @@ struct EmulatorKeybindings {
 class Emulator {
  public:
   Emulator() = default;
-  ~Emulator() = default;
+  ~Emulator();
   void Initialize(gfx::IRenderer* renderer, const std::vector<uint8_t>& rom_data);
   void Run(Rom* rom);
+  void Cleanup();
 
   auto snes() -> Snes& { return snes_; }
   auto running() const -> bool { return running_; }