refactor: move world concepts into engine

engine/render/RenderConfig.ts

@@ -46,10 +46,8 @@ export type RenderConfig = {
    *  short draw distance and the shimmer of far geometry. It also colors pixels
    *  no triangle covers, so the frame's clear color should match `fog.color`. */
   fog: Fog | null
-  /** Beyond this distance (world units) trees + boulders draw as cheap low-poly
-   *  impostors instead of full geometry, cutting per-triangle work in dense
-   *  views. Kept inside `fog.far` so far detail is already fog-dimmed at the
-   *  switch; `Infinity` disables LOD. */
+  /** Beyond this distance (world units), chunks draw their cheaper far groups
+   *  instead of near geometry. `Infinity` disables LOD. */
   lodDistance: number
 }