Add power plant background

src/battle-scene.ts

@@ -332,7 +332,7 @@ export default class BattleScene extends Phaser.Scene {
 				this.loadAtlas(baseBKey, 'arenas');
 			if (getBiomeHasProps(bt)) {
 				for (let p = 1; p <= 3; p++) {
-					const isPropAnimated = p === 3 && btKey === 'end';
+					const isPropAnimated = p === 3 && [ 'power_plant', 'end' ].find(b => b === btKey);
 					const propKey = `${btKey}_b_${p}`;
 					if (!isPropAnimated)
 						this.loadImage(propKey, 'arenas');

src/field/arena.ts

@@ -564,8 +564,6 @@ export class Arena {
 
 export function getBiomeKey(biome: Biome): string {
   switch (biome) {
-    case Biome.POWER_PLANT:
-      return 'ruins';
     case Biome.METROPOLIS:
       return 'slum';
     case Biome.JUNGLE:
@@ -587,6 +585,7 @@ export function getBiomeHasProps(biomeType: Biome): boolean {
     case Biome.DESERT:
     case Biome.ICE_CAVE:
     case Biome.MEADOW:
+    case Biome.POWER_PLANT:
     case Biome.VOLCANO:
     case Biome.GRAVEYARD:
     case Biome.FACTORY: