fix(dirtfx): support IVF dirt overlays and paintjobs safely

[CanerKaraca23]

Summary

Enhances DirtFx compatibility to support ImVehFt (IVF) style dirt overlays and vehicle texture remapping / paintjobs simultaneously and safely.

Details

• Preserves active remap/paintjob textures when generating and swapping dirt texture stages.
• Handles dirt stage blending across multiple materials and paintjob variations without texture corruption or memory leaks.