feat(game): 添加全套音效系统（背景BGM+7种攻击音+波次/Boss/死亡/建塔音效），纯Web Audio API合成

game/towers/InternTower.ts

@@ -1,6 +1,7 @@
 import type Phaser from 'phaser'
 import { TowerBase } from './TowerBase'
 import { GameManager } from '../GameManager'
+import { AudioEngine } from '../AudioEngine'
 import type { EnemyBase } from '../enemies/EnemyBase'
 
 export class InternTower extends TowerBase {
@@ -32,6 +33,7 @@ export class InternTower extends TowerBase {
   }
 
   attack(target: EnemyBase): void {
+    AudioEngine.getInstance().playPunch()
     const isInstakill = Math.random() < 0.05 && target.hp < 500
     if (isInstakill) {
       target.takeDamage(9999)