feat(ui): 사망 화면 잃은 아이템 희귀도 색상 표시

- DeathInfo에 lostItemRarity 필드 추가
- 사망 처리 시 아이템 희귀도 저장
- 사망 오버레이에서 희귀도별 색상 적용
  - Common: 회색, Uncommon: 녹색, Rare: 파랑
  - Epic: 보라, Legendary: 주황

lib/src/features/game/widgets/death_overlay.dart

@@ -5,6 +5,7 @@ import 'package:asciineverdie/src/core/l10n/game_data_l10n.dart';
 import 'package:asciineverdie/src/core/model/combat_event.dart';
 import 'package:asciineverdie/src/core/model/equipment_slot.dart';
 import 'package:asciineverdie/src/core/model/game_state.dart';
+import 'package:asciineverdie/src/core/model/item_stats.dart';
 import 'package:asciineverdie/src/shared/retro_colors.dart';
 
 /// 사망 오버레이 위젯 (Phase 4)
@@ -294,10 +295,8 @@ class DeathOverlay extends StatelessWidget {
     final expColor = RetroColors.expOf(context);
     final gold = RetroColors.goldOf(context);
 
-    // 슬롯명 + 아이템명 조합
-    final lostItemDisplay = hasLostItem
-        ? '[${_getSlotName(deathInfo.lostItemSlot)}] ${deathInfo.lostItemName}'
-        : null;
+    // 희귀도에 따른 아이템 이름 색상
+    final itemRarityColor = _getRarityColor(deathInfo.lostItemRarity);
 
     return Column(
       children: [
@@ -326,12 +325,23 @@ class DeathOverlay extends StatelessWidget {
                         ),
                       ),
                       const SizedBox(height: 4),
-                      Text(
-                        lostItemDisplay!,
-                        style: TextStyle(
+                      // 슬롯명 (회색) + 아이템명 (희귀도 색상)
+                      Text.rich(
+                        TextSpan(
+                          children: [
+                            TextSpan(
+                              text: '[${_getSlotName(deathInfo.lostItemSlot)}] ',
+                              style: TextStyle(color: muted),
+                            ),
+                            TextSpan(
+                              text: deathInfo.lostItemName!,
+                              style: TextStyle(color: itemRarityColor),
+                            ),
+                          ],
+                        ),
+                        style: const TextStyle(
                           fontFamily: 'PressStart2P',
                           fontSize: 13,
-                          color: hpColor,
                         ),
                       ),
                     ],
@@ -695,4 +705,16 @@ class DeathOverlay extends StatelessWidget {
       EquipmentSlot.sollerets => l10n.slotSollerets,
     };
   }
+
+  /// 희귀도에 따른 색상 반환
+  Color _getRarityColor(ItemRarity? rarity) {
+    if (rarity == null) return Colors.grey;
+    return switch (rarity) {
+      ItemRarity.common => Colors.grey,
+      ItemRarity.uncommon => Colors.green,
+      ItemRarity.rare => Colors.blue,
+      ItemRarity.epic => Colors.purple,
+      ItemRarity.legendary => Colors.orange,
+    };
+  }
 }