fix(graphics): tune presets, single-line ui, vegetation LOD by nearest instance

- Bump high to 30m chunk / HD<20m and ultra to HD<30m so HD models
  persist further before swapping.
- Render the 5 graphics preset cards on a single row.
- Vegetation LOD selection now uses the distance to the nearest instance
  in each chunk instead of the chunk centre, matching MapInstancingSystem
  and avoiding premature LOD swaps when the camera enters a chunk.

src/index.css

@@ -1544,7 +1544,7 @@ canvas {
 }
 
 .game-settings-menu__choice-group--presets {
-  grid-template-columns: repeat(4, minmax(0, 1fr));
+  grid-template-columns: repeat(5, minmax(0, 1fr));
 }
 
 .game-settings-menu__choice-group button,