Function skyForAltitude

skyForAltitude(altitudeDeg: number, fogColor: string): SkySpec
Derive the MapLibre sky/fog tint from the sun altitude.
Parameters
- altitudeDeg: number
  Solar altitude above the horizon, degrees (negative below it).
- fogColor: string
  The fog colour to use, a CSS string — pass the direct sun colour (SunState.color) so terrain fog warms at golden hour.
Returns SkySpec
A SkySpec ready to hand to map.setSky.