Graphics presets and a clearer extraction marker

Shattered Rift now offers High, Balanced and Performance graphics choices in the menu, and the HUD stays sharp whichever you pick. We also moved the extraction label and arrow so they stay clear of the canyon discovery panel. The screenshots show it before and after. Shield hits now reuse prepared arcs and lights instead of creating new ones on every hit. Frame pacing in moving canyon scenes and loading speed still miss our targets.