Add anaglyph 3D post-processing effect support

[yoavfrancis]

Summary

This PR adds anaglyph (red-cyan) 3D post-processing support to the game engine, enabling stereoscopic 3D viewing with compatible glasses.

Key Changes

• New SurfaceProxy::applyAnaglyph3D() method: Implements red-cyan anaglyph 3D effect by combining two horizontally-shifted versions of the rendered frame into separate color channels

  • Left eye uses the red channel from source shifted right
  • Right eye uses green+blue channels from source shifted left
  • Configurable pixel shift parameter (default: 5 pixels) for stereo separation control

• Engine rendering pipeline refactored:

  • Added m_renderTarget off-screen surface to Engine for intermediate rendering
  • Game scene now renders to m_renderTarget instead of directly to screen
  • Anaglyph post-processing applied each frame to combine m_renderTarget into m_screen
  • Proper resource cleanup added to Engine destructor

Implementation Details

• The anaglyph effect works by creating a stereoscopic illusion through color channel separation, allowing users with red-cyan 3D glasses to perceive depth
• Surfaces are properly locked during pixel manipulation for thread safety
• Boundary checking prevents out-of-bounds access when applying horizontal shifts
• The post-processing is applied after scene drawing but before screen flip, maintaining the existing frame timing

https://claude.ai/code/session_01JyqcqkChDKjYQeYzHYZcnH