feat: implement Music and SoundEffects systems for enhanced audio management, including background music and sound effects playback

src/systems/SkillSystem.ts

@@ -1,6 +1,7 @@
 import { System } from '../core/System.ts';
 import { SkillRegistry } from '../skills/SkillRegistry.ts';
 import { SystemName, ComponentType } from '../core/Constants.ts';
+import { Events } from '../core/EventBus.ts';
 import type { Entity } from '../core/Entity.ts';
 import type { Skills } from '../components/Skills.ts';
 import type { Intent } from '../components/Intent.ts';
@@ -55,6 +56,7 @@ export class SkillSystem extends System {
       if (skills) {
         skills.setCooldown(skillId, skill.cooldown);
       }
+      this.engine.emit(Events.SKILL_COOLDOWN_STARTED, { skillId });
     }
   }
 }