feat(skill): DamageType 및 magAtk/magDef 스킬 시스템 추가

- DamageType enum 추가 (physical/magical)
- 스킬별 데미지 타입 지정 기능 구현
- 마법 스킬 데미지에 magAtk/magDef 적용
- 장비 아이템에서 magAtk/magDef 스탯 추출
- 관련 테스트 업데이트

test/core/engine/skill_service_test.dart

@@ -103,6 +103,7 @@ void main() {
           level: 1,
           atk: 10,
           def: 50, // DEF 50 → 50 * 0.3 = 15 감소
+          magDef: 50,
           hpMax: 500,
           hpCurrent: 500,
           criRate: 0.05,
@@ -124,7 +125,7 @@ void main() {
         // ATK 100 * 2.0 - DEF 50 * 0.3 = 200 - 15 = 185
         expect(result.result.success, isTrue);
         expect(result.result.damage, equals(185));
-        expect(result.updatedPlayer.mpCurrent, equals(40)); // 50 - 10
+        expect(result.updatedPlayer.mpCurrent, equals(20)); // 50 - 30 (mpCost 30)
         expect(result.updatedMonster.hpCurrent, equals(315)); // 500 - 185
       });
 
@@ -143,6 +144,7 @@ void main() {
           level: 1,
           atk: 10,
           def: 0,
+          magDef: 0,
           hpMax: 500,
           hpCurrent: 500,
           criRate: 0.05,
@@ -196,6 +198,7 @@ void main() {
           level: 1,
           atk: 10,
           def: 0,
+          magDef: 0,
           hpMax: 500,
           hpCurrent: 500,
           criRate: 0.05,
@@ -217,7 +220,7 @@ void main() {
 
         // 랭크 1: 1.0x → ATK 100 * 2.0 * 1.0 = 200
         expect(result.result.damage, equals(200));
-        expect(result.updatedPlayer.mpCurrent, equals(40)); // MP 10 소모
+        expect(result.updatedPlayer.mpCurrent, equals(20)); // MP 30 소모
       });
 
       test('랭크 5 데미지 스케일링', () {
@@ -235,6 +238,7 @@ void main() {
           level: 1,
           atk: 10,
           def: 0,
+          magDef: 0,
           hpMax: 500,
           hpCurrent: 500,
           criRate: 0.05,
@@ -254,12 +258,12 @@ void main() {
           rank: 5,
         );
 
-        // 랭크 5: 1.6x (1.0 + 4 * 0.15)
-        // ATK 100 * 2.0 * 1.6 = 320
-        expect(result.result.damage, equals(320));
+        // 랭크 5: 1.32x (1.0 + 4 * 0.08) - 랭크 배율 하향
+        // ATK 100 * 2.0 * 1.32 = 264
+        expect(result.result.damage, equals(264));
 
-        // MP 비용: 10 * (1.0 - 4 * 0.03) = 10 * 0.88 = 9 (반올림)
-        expect(result.updatedPlayer.mpCurrent, equals(41)); // 50 - 9
+        // MP 비용: 30 * (1.0 - 4 * 0.03) = 30 * 0.88 = 26 (반올림)
+        expect(result.updatedPlayer.mpCurrent, equals(24)); // 50 - 26
       });
     });
 
@@ -268,12 +272,12 @@ void main() {
         final rng = DeterministicRandom(42);
         final service = SkillService(rng: rng);
 
-        const skill = SkillData.hotReload; // healAmount: 30
+        const skill = SkillData.hotReload; // healAmount: 30, mpCost: 80
         final player = CombatStats.empty().copyWith(
           hpMax: 200,
           hpCurrent: 100,
-          mpMax: 100,
-          mpCurrent: 50,
+          mpMax: 200,
+          mpCurrent: 150,
         );
         final skillSystem = SkillSystemState.empty().copyWith(elapsedMs: 5000);
 
@@ -286,7 +290,7 @@ void main() {
         expect(result.result.success, isTrue);
         expect(result.result.healedAmount, equals(30));
         expect(result.updatedPlayer.hpCurrent, equals(130)); // 100 + 30
-        expect(result.updatedPlayer.mpCurrent, equals(35)); // 50 - 15
+        expect(result.updatedPlayer.mpCurrent, equals(70)); // 150 - 80
       });
 
       test('퍼센트 회복량', () {
@@ -483,6 +487,7 @@ void main() {
           level: 1,
           atk: 10,
           def: 10,
+          magDef: 10,
           hpMax: 100,
           hpCurrent: 100,
           criRate: 0.05,
@@ -512,14 +517,15 @@ void main() {
         final player = CombatStats.empty().copyWith(
           hpMax: 100,
           hpCurrent: 20, // 20% HP
-          mpMax: 100,
-          mpCurrent: 80,
+          mpMax: 200,
+          mpCurrent: 150, // 힐 스킬 사용 가능한 MP (garbageCollection: 130)
         );
         final monster = MonsterCombatStats(
           name: 'Test Monster',
           level: 1,
           atk: 10,
           def: 10,
+          magDef: 10,
           hpMax: 100,
           hpCurrent: 100,
           criRate: 0.05,
@@ -548,10 +554,10 @@ void main() {
         final rng = DeterministicRandom(42);
         final service = SkillService(rng: rng);
 
-        const skill = SkillData.debugMode; // ATK +25% 버프
+        const skill = SkillData.debugMode; // ATK +25% 버프, mpCost: 100
         final player = CombatStats.empty().copyWith(
-          mpMax: 100,
-          mpCurrent: 50,
+          mpMax: 200,
+          mpCurrent: 150,
         );
         final skillSystem = SkillSystemState.empty().copyWith(elapsedMs: 5000);
 
@@ -568,7 +574,7 @@ void main() {
           equals(0.25),
         );
         expect(result.updatedSkillSystem.activeBuffs.length, equals(1));
-        expect(result.updatedPlayer.mpCurrent, equals(30)); // 50 - 20
+        expect(result.updatedPlayer.mpCurrent, equals(50)); // 150 - 100
       });
 
       test('중복 버프 제거 후 새 버프 적용', () {
@@ -648,11 +654,12 @@ void main() {
 
     group('getRankMultiplier', () {
       test('랭크별 배율 계산', () {
+        // 랭크 배율 하향: 0.15 → 0.08 per rank
         expect(getRankMultiplier(1), equals(1.0));
-        expect(getRankMultiplier(2), closeTo(1.15, 0.001));
-        expect(getRankMultiplier(3), closeTo(1.30, 0.001));
-        expect(getRankMultiplier(5), closeTo(1.60, 0.001));
-        expect(getRankMultiplier(10), closeTo(2.35, 0.001));
+        expect(getRankMultiplier(2), closeTo(1.08, 0.001));
+        expect(getRankMultiplier(3), closeTo(1.16, 0.001));
+        expect(getRankMultiplier(5), closeTo(1.32, 0.001));
+        expect(getRankMultiplier(10), closeTo(1.72, 0.001));
       });
     });