Refactor rendering pipeline and update pie menu shader
- Split Render::render into render and finalPass to better manage multiple scenes.
- Move post-processing and frame flushing into Render::finalPass.
- Update pie menu shader to rotate center icon based on mouse angle.
- Enable VSync by default in ResetFlags.
- Change screen pass clear color to black.
- Mark axe and bow SFX tasks as completed in todo.md.