refactor(engine): 서비스 로직 정리

- ArenaService, PotionService, ProgressService 개선
- ResurrectionService, SkillService 정리

lib/src/core/engine/potion_service.dart

@@ -375,8 +375,10 @@ class PotionService {
     required int typeRoll,
   }) {
     // 기본 드랍 확률 계산
-    var dropChance = (baseDropChance + playerLevel * dropChancePerLevel)
-        .clamp(baseDropChance, maxDropChance);
+    var dropChance = (baseDropChance + playerLevel * dropChancePerLevel).clamp(
+      baseDropChance,
+      maxDropChance,
+    );
 
     // 몬스터 등급 보너스 (Elite +5%, Boss +15%)
     dropChance += monsterGrade.potionDropBonus;