fix(game): 修复格子正方形和图片尺寸问题，用setDisplaySize精确控制角色图片占一格

game/enemies/OldEmployee.ts

@@ -6,9 +6,8 @@ export class OldEmployee extends EnemyBase {
   constructor(scene: Phaser.Scene, pathPoints: PathPoint[]) {
     super(scene, pathPoints, 150, 50, 8, 30, 'enemy-old')
     this.shieldCount = 3
-    // 老员工图片稍大
-    const scale = Math.min(this.cellW, this.cellH) / 128 * 0.9
-    this.imageSprite.setScale(scale)
+    // 老员工比普通怪略大（0.85 个格子）
+    this.imageSprite.setDisplaySize(this.cellW * 0.85, this.cellW * 0.85)
   }
 
   getQuote(): string { return getRandomQuote('OldEmployee') }