docs: document Armada Odin 2 LSFG presentation corruption

[Janleyx]

Summary

This PR documents the reproducible LSFG-VK presentation corruption seen on an AYN Odin 2 Pro running Armada Linux.

It includes:

• exact device, kernel, Mesa Turnip, Gamescope, Proton, PEAK, and profile details;
• clean-vs-enabled reproduction steps;
• benchmark evidence showing the LSFG pipeline itself runs on Turnip;
• all tested WSI, present-mode, pNext, layout, performance, image-count, and upstream-layer variants;
• the related Armada Gamescope regression and its timing;
• a clear separation between verified facts and remaining hypotheses.

No experimental binary or speculative behavior change is included. The report is intended to make follow-up testing and an upstream bug report easier.