Biome fight fields and a new art pass on story backgrounds

Story scenes—the places where you walk the hubs and explore—now use new background art with an updated overall look. That work lives on the exploration layer, not on the tactical UI.

Fights—the turn-based grid—now key off biomes: each encounter can specify a biome, and the fight field shows the matching wide backdrop behind the panels so the arena feels like its own location.

Battles, as the narrative encounter layer around a fight, are still their own thing in how the game is structured. This update is about environment art for story spaces and biome art for the fight field, not treating those three surfaces as the same screen.