[MGG] Biome Selector

Smooth Terrain Update

• Improved biome transition smoothing for more natural terrain generation.
• Smoothed ocean-to-land elevation changes to reduce harsh cliffs and sudden terrain walls.
• Improved coastline blending while keeping beaches and shallow-water areas reasonably sized.
• Added longer terrain transition ramps so neighboring biome heights blend more gradually.
• Preserved each biome's native Hytale terrain, materials, foliage, structures, and overall identity.
• Improved Mixed biome generation so extreme biome combinations remain dramatic without creating as many abrupt or blocky transitions.
• Terrain smoothing is applied only where needed near biome boundaries to minimize unnecessary world-generation changes.