feat(balance): 스킬 버프 모디파이어 3종 전투 적용

- defModifier: 몬스터 반격 시 방어력 배율 적용 (DEF × (1+defMod))
- criRateModifier: 플레이어 공격 시 크리티컬 확률 추가
- evasionModifier: 몬스터 반격 시 회피율 추가
- 기존 atkModifier 패턴과 동일하게 임시 적용 + HP/MP만 반영

lib/src/core/engine/combat_tick_service.dart

@@ -125,12 +125,22 @@ class CombatTickService {
       newEvents.addAll(potionResult.events);
     }
 
+    // 스킬 버프 모디파이어 조회 (전투 계산에 적용)
+    final buffMods = updatedSkillSystem.totalBuffModifiers;
+
     // 플레이어 공격 체크
     if (playerAccumulator >= playerStats.attackDelayMs) {
+      // 크리티컬 확률 버프 적용
+      final buffedPlayerForAttack = buffMods.criMod != 0
+          ? playerStats.copyWith(
+              criRate: (playerStats.criRate + buffMods.criMod).clamp(0.0, 1.0),
+            )
+          : playerStats;
+
       final attackProcessor = PlayerAttackProcessor(rng: rng);
       final attackResult = attackProcessor.processAttack(
         state: state,
-        playerStats: playerStats,
+        playerStats: buffedPlayerForAttack,
         monsterStats: monsterStats,
         updatedSkillSystem: updatedSkillSystem,
         activeDoTs: activeDoTs,
@@ -145,7 +155,14 @@ class CombatTickService {
         healingMultiplier: healingMultiplier,
       );
 
-      playerStats = attackResult.playerStats;
+      // 크리티컬 버프가 적용된 스탯에서 HP/MP만 원본에 반영
+      final attackedPlayer = attackResult.playerStats;
+      playerStats = buffMods.criMod != 0
+          ? playerStats.copyWith(
+              hpCurrent: attackedPlayer.hpCurrent,
+              mpCurrent: attackedPlayer.mpCurrent,
+            )
+          : attackedPlayer;
       monsterStats = attackResult.monsterStats;
       updatedSkillSystem = attackResult.skillSystem;
       activeDoTs = attackResult.activeDoTs;
@@ -161,8 +178,18 @@ class CombatTickService {
     // 몬스터가 살아있으면 반격
     if (monsterStats.isAlive &&
         monsterAccumulator >= monsterStats.attackDelayMs) {
+      // 방어력/회피율 버프 적용
+      final buffedPlayerForDefense = (buffMods.defMod != 0 ||
+              buffMods.evasionMod != 0)
+          ? playerStats.copyWith(
+              def: (playerStats.def * (1.0 + buffMods.defMod)).round(),
+              evasion: (playerStats.evasion + buffMods.evasionMod)
+                  .clamp(0.0, 1.0),
+            )
+          : playerStats;
+
       final monsterAttackResult = _processMonsterAttack(
-        playerStats: playerStats,
+        playerStats: buffedPlayerForDefense,
         monsterStats: monsterStats,
         activeDebuffs: activeDebuffs,
         totalDamageTaken: totalDamageTaken,
@@ -170,7 +197,12 @@ class CombatTickService {
         calculator: calculator,
       );
 
-      playerStats = monsterAttackResult.playerStats;
+      // 버프 적용된 스탯에서 HP/MP만 원본에 반영
+      final defendedPlayer = monsterAttackResult.playerStats;
+      playerStats = playerStats.copyWith(
+        hpCurrent: defendedPlayer.hpCurrent,
+        mpCurrent: defendedPlayer.mpCurrent,
+      );
       totalDamageTaken = monsterAttackResult.totalDamageTaken;
       newEvents.addAll(monsterAttackResult.events);
       monsterAccumulator -= monsterStats.attackDelayMs;