External Backgrounds & Input Config Improvements

This release brings support for background images on external displays and introduces significant UX improvements to the input configuration screen.

New Features

External Display Background Support

• You can now set custom background images for external displays.
• Backgrounds are loaded, scaled, and rendered efficiently.
• Background rendering occurs before the screen layers, ensuring proper visual layering.
• Changes are managed via RuntimeBackground, BackgroundMode, and observed by EmulatorViewModel.

Input Configuration UX Improvements

• "Waiting for Input" Overlay:
  A semi-transparent overlay now appears when mapping controls, showing a clear prompt and a Cancel button to abort the process.

• Improved Key Handling:
  Key events are intercepted at the Activity level, allowing mapping of all buttons, including system-level keys (like the back button).

These changes improve the visual experience on external displays and streamline controller configuration for all users.