Smoother loading for damaged worlds

Loading damaged worlds in Shattered Rift is now more responsive, with the original geometry and ship mount positions preserved. In one short comparison, the worst loading frame for world fragments dropped from 198 ms to 23 ms, and for ship rigs from 246 ms to 68 ms. Total load time rose slightly, to 11.51 seconds, and streaming still causes a 194 ms hitch, so our 3-second load and 60 FPS targets remain open. The screenshot is from the player camera.