feat: drs based upscaling

[doodlum]

Summary by CodeRabbit

• New Features

  • Full Upscaling subsystem with multi-backend support (DLSS/XeSS/FSR), frame-generation, new upscaling shaders and runtime UI.

• Improvements

  • Dynamic, resolution-aware screen-space shadows and VR-aware sampling.
  • VR-aware dynamic light cluster sizing, improved depth handling and ReShade integration.
  • Per-feature lifecycle and D3D interop refinements.

• Bug Fixes

  • Fixed UV/eye-index ordering and depth-source selection across render passes.

• Chores

  • Added XeSS support, DirectX headers/vcpkg port, updated licenses, and .gitignore entry for local settings.