Function: initBodySimulation()

function initBodySimulation(
   tiles, 
   config, 
   atmoTiles?): BodySimulation;

Deterministically derives a BodySimulation from a seed/config and a pre-generated tile mesh.

Three-step pipeline:

Sample seeded simplex noise for every tile.
Rank tiles into N equal-frequency bands (elevation 0..N-1), where N is derived from (radius, coreRadiusRatio) via resolveTerrainLevelCount (render layer).
Resolve liquid coverage → a band-space sea waterline + assemble the immutable TileState map.

Parameters

Parameter	Type	Default value	Description
`tiles`	`Tile`[]	`undefined`	Hexasphere tiles produced by `generateHexasphere`.
`config`	`BodyConfig`	`undefined`	Full body physics/visual configuration.
`atmoTiles`	readonly `Tile`[]	`[]`	-