[Runtime Feature]: Add Markov Chain Path Guiding in Remix

What is the context of the feature/improvement?

In April of this year, a new light caching technology was released called Markov Chain Path Guiding. This technology has quite a few pros that I was able to discover recently, and also one disadvantage.

Please describe the feature/improvement?

Pros:
*Caustics and volumetric caustics

*Excellent performance
Quake with path tracing and this technology without upscaling runs at no less than 30 fps and has a stable frame time (it is worth considering that this was tested on RX 70 series cards, as well as on RTX 20 series cards)

*Quick change of lighting
I was also surprised by the refresh rate of the lights, as well as the caustics, which updated in milliseconds and without any visible ghosting.

Minus:
*Problem with a large number of light sources
The member of the server noted that the document states that this technology cannot handle a large number of light sources and that ReSTIR DI handles this best

What would be your solution? (optional)

No response

Version

1.0.0

Media

PDF file:
https://jo.dreggn.org/home/2025_mcpg.pdf
Blog:
https://www.lalber.org/2025/04/markov-chain-path-guiding/
Videos:
https://youtu.be/iXk3AG5tsDY?si=juRKRb2DSS9iu2Zf
https://youtu.be/n32fyCeqkII?si=6wILS-DYEjZbTQmI

Start by reading the linked PDF and blog to understand Markov Chain Path Guiding, then map the runtime's current path-tracing and lighting implementation. Define how the feature should address caustics, volumetric caustics, rapid lighting changes, and many-light-source behavior; the issue currently provides no file, test, or acceptance criteria.