Globe rendering and scene foundation

Today was mostly about getting the visual core solid. I added the full camera, renderer, post‑processing composer, and resize handling, with a quick quality detection switch so it doesn’t melt phones. The earth now uses a “black marble” model: a dark body, and a separate night‑lights layer on top that blends. A fixed sun rig keeps the day‑night terminator moving as the globe rotates, which makes the whole thing feel alive. The starfield got a rewrite too, but it still needs polish, but the foundation finally feels solid.