Optimize initial loading performance

src/game/scenes/BootScene.ts

@@ -1,7 +1,5 @@
 import Phaser from 'phaser';
 import titleBackgroundUrl from '../../assets/images/taoyuan-oath-title.png';
-import { portraitAssets } from '../data/portraitAssets';
-import { storyBackgroundAssets } from '../data/storyAssets';
 
 export class BootScene extends Phaser.Scene {
   constructor() {
@@ -10,8 +8,6 @@ export class BootScene extends Phaser.Scene {
 
   preload() {
     this.load.image('title-taoyuan', titleBackgroundUrl);
-    this.load.image('story-militia', storyBackgroundAssets['story-militia']);
-    Object.entries(portraitAssets).forEach(([key, url]) => this.load.image(`portrait-${key}`, url));
   }
 
   create() {