feat(core): i18n 및 핵심 로직 개선

- 수익화 관련 텍스트 추가
- item_service 수정
- progress_service 수정

lib/src/core/engine/progress_service.dart

@@ -972,12 +972,16 @@ class ProgressService {
     String? lostItemName;
     EquipmentSlot? lostItemSlot;
     ItemRarity? lostItemRarity;
+    EquipmentItem? lostEquipmentItem; // 광고 부활 시 복구용
 
     if (!isBossDeath) {
       // 레벨 기반 장비 손실 확률 계산
-      // Lv 1~5: 0%, Lv 6: 10%, Lv 10: 50%, Lv 15+: 100%
+      // Lv 1: 20%, Lv 5: ~56%, Lv 10+: 100%
+      // 공식: 20 + (level - 1) * 80 / 9
       final level = state.traits.level;
-      final lossChancePercent = ((level - 5) * 10).clamp(0, 100);
+      final lossChancePercent = level >= 10
+          ? 100
+          : (20 + ((level - 1) * 80 ~/ 9)).clamp(0, 100);
       final roll = state.rng.nextInt(100); // 0~99
       final shouldLoseEquipment = roll < lossChancePercent;
 
@@ -1004,10 +1008,10 @@ class ProgressService {
               )];
 
           // 제물로 바칠 아이템 정보 저장
-          final lostItem = state.equipment.getItemByIndex(sacrificeIndex);
-          lostItemName = lostItem.name;
+          lostEquipmentItem = state.equipment.getItemByIndex(sacrificeIndex);
+          lostItemName = lostEquipmentItem.name;
           lostItemSlot = EquipmentSlot.values[sacrificeIndex];
-          lostItemRarity = lostItem.rarity;
+          lostItemRarity = lostEquipmentItem.rarity;
 
           // 해당 슬롯을 빈 장비로 교체
           newEquipment = newEquipment.setItemByIndex(
@@ -1029,6 +1033,7 @@ class ProgressService {
       lostItemName: lostItemName,
       lostItemSlot: lostItemSlot,
       lostItemRarity: lostItemRarity,
+      lostItem: lostEquipmentItem, // 광고 부활 시 복구용
       goldAtDeath: state.inventory.gold,
       levelAtDeath: state.traits.level,
       timestamp: state.skillSystem.elapsedMs,