feat(arena): 아레나 화면 및 위젯 개선

- 장비 비교 리스트 UI 개선
- 결과 패널/다이얼로그 업데이트
- 설정 화면 개선

lib/src/features/arena/arena_setup_screen.dart

@@ -55,9 +55,12 @@ class _ArenaSetupScreenState extends State<ArenaSetupScreen> {
   /// 자동 결정된 상대
   HallOfFameEntry? _opponent;
 
-  /// 선택된 베팅 슬롯
+  /// 선택된 베팅 슬롯 (도전자가 상대에게서 뺏을 슬롯)
   EquipmentSlot? _selectedSlot;
 
+  /// 상대가 선택한 베팅 슬롯 (패배 시 뺏길 슬롯)
+  EquipmentSlot? _opponentBettingSlot;
+
   @override
   void initState() {
     super.initState();
@@ -71,9 +74,13 @@ class _ArenaSetupScreenState extends State<ArenaSetupScreen> {
   void _selectChallenger(HallOfFameEntry entry) {
     final opponent = _arenaService.findOpponent(widget.hallOfFame, entry.id);
 
+    // AI가 도전자에게서 약탈할 슬롯 미리 계산
+    final opponentSlot = _arenaService.selectOpponentBettingSlot(entry);
+
     setState(() {
       _challenger = entry;
       _opponent = opponent;
+      _opponentBettingSlot = opponentSlot;
       _step = 1;
     });
   }
@@ -81,14 +88,16 @@ class _ArenaSetupScreenState extends State<ArenaSetupScreen> {
   void _startBattle() {
     if (_challenger == null ||
         _opponent == null ||
-        _selectedSlot == null) {
+        _selectedSlot == null ||
+        _opponentBettingSlot == null) {
       return;
     }
 
     final match = ArenaMatch(
       challenger: _challenger!,
       opponent: _opponent!,
-      bettingSlot: _selectedSlot!,
+      challengerBettingSlot: _selectedSlot!,
+      opponentBettingSlot: _opponentBettingSlot!,
     );
 
     final navigator = Navigator.of(context);
@@ -188,7 +197,7 @@ class _ArenaSetupScreenState extends State<ArenaSetupScreen> {
         ),
         // 상단 캐릭터 정보 (좌우 대칭)
         _buildCharacterHeaders(),
-        // 장비 비교 리스트
+        // 장비 비교 리스트 (양방향 베팅 표시 포함)
         Expanded(
           child: Padding(
             padding: const EdgeInsets.symmetric(horizontal: 12),
@@ -197,6 +206,7 @@ class _ArenaSetupScreenState extends State<ArenaSetupScreen> {
               enemyEquipment: _opponent?.finalEquipment,
               selectedSlot: _selectedSlot,
               recommendedSlot: recommendedSlot,
+              opponentBettingSlot: _opponentBettingSlot,
               onSlotSelected: (slot) {
                 setState(() => _selectedSlot = slot);
               },
@@ -209,14 +219,16 @@ class _ArenaSetupScreenState extends State<ArenaSetupScreen> {
     );
   }
 
-  /// 추천 슬롯 계산 (점수 이득이 가장 큰 슬롯)
+  /// 추천 슬롯 계산 (점수 이득이 가장 큰 슬롯, 무기 제외)
   EquipmentSlot? _calculateRecommendedSlot() {
     if (_challenger == null || _opponent == null) return null;
 
     EquipmentSlot? bestSlot;
     int maxGain = 0;
 
-    for (final slot in EquipmentSlot.values) {
+    // 베팅 가능한 슬롯만 검사 (무기 제외)
+    final bettableSlots = _arenaService.getBettableSlots();
+    for (final slot in bettableSlots) {
       final myItem = _findItem(slot, _challenger!.finalEquipment);
       final enemyItem = _findItem(slot, _opponent!.finalEquipment);
 

lib/src/features/arena/widgets/arena_equipment_compare_list.dart

@@ -11,6 +11,7 @@ const _myEquipmentTitle = 'MY EQUIPMENT';
 const _enemyEquipmentTitle = 'ENEMY EQUIPMENT';
 const _selectedLabel = 'SELECTED';
 const _recommendedLabel = 'BEST';
+const _weaponLockedLabel = 'LOCKED';
 
 /// 좌우 대칭 장비 비교 리스트
 ///
@@ -24,6 +25,7 @@ class ArenaEquipmentCompareList extends StatefulWidget {
     required this.selectedSlot,
     required this.onSlotSelected,
     this.recommendedSlot,
+    this.opponentBettingSlot,
   });
 
   /// 내 장비 목록
@@ -32,7 +34,7 @@ class ArenaEquipmentCompareList extends StatefulWidget {
   /// 상대 장비 목록
   final List<EquipmentItem>? enemyEquipment;
 
-  /// 현재 선택된 슬롯
+  /// 현재 선택된 슬롯 (내가 상대에게서 뺏을 슬롯)
   final EquipmentSlot? selectedSlot;
 
   /// 슬롯 선택 콜백
@@ -41,6 +43,9 @@ class ArenaEquipmentCompareList extends StatefulWidget {
   /// 추천 슬롯 (점수 이득이 가장 큰 슬롯)
   final EquipmentSlot? recommendedSlot;
 
+  /// 상대가 선택한 슬롯 (패배 시 내가 잃을 슬롯)
+  final EquipmentSlot? opponentBettingSlot;
+
   @override
   State<ArenaEquipmentCompareList> createState() =>
       _ArenaEquipmentCompareListState();
@@ -162,6 +167,14 @@ class _ArenaEquipmentCompareListState extends State<ArenaEquipmentCompareList> {
     final isSelected = widget.selectedSlot == slot;
     final isRecommended = widget.recommendedSlot == slot;
 
+    // 무기 슬롯은 선택 불가 (보호됨)
+    final isLocked = slot == EquipmentSlot.weapon;
+
+    // 양방향 베팅 상태
+    final isMyTarget = isSelected; // 내가 선택 = 상대 장비 획득 예정
+    final isOpponentTarget =
+        widget.opponentBettingSlot == slot; // 상대가 선택 = 내 장비 손실 예정
+
     final myScore =
         myItem != null ? ItemService.calculateEquipmentScore(myItem) : 0;
     final enemyScore =
@@ -172,29 +185,29 @@ class _ArenaEquipmentCompareListState extends State<ArenaEquipmentCompareList> {
       children: [
         // 슬롯 행 (좌우 대칭)
         GestureDetector(
-          onTap: () {
+          onTap: isLocked
-            // 탭하면 즉시 선택 + 확장 + 자동 스크롤
+              ? null
-            widget.onSlotSelected(slot);
+              : () {
-            setState(() {
+                  // 탭하면 즉시 선택 + 확장 + 자동 스크롤
-              _expandedSlot = isExpanded ? null : slot;
+                  widget.onSlotSelected(slot);
-            });
+                  setState(() {
-            // 확장될 때만 스크롤 (다음 프레임에서 실행)
+                    _expandedSlot = isExpanded ? null : slot;
-            if (!isExpanded) {
+                  });
-              WidgetsBinding.instance.addPostFrameCallback((_) {
+                  // 확장될 때만 스크롤 (다음 프레임에서 실행)
-                _scrollToSlot(slot);
+                  if (!isExpanded) {
-              });
+                    WidgetsBinding.instance.addPostFrameCallback((_) {
-            }
+                      _scrollToSlot(slot);
-          },
+                    });
+                  }
+                },
           child: Container(
             padding: const EdgeInsets.symmetric(vertical: 6, horizontal: 4),
             decoration: BoxDecoration(
-              color: isSelected
+              color: isLocked
-                  ? RetroColors.goldOf(context).withValues(alpha: 0.2)
+                  ? RetroColors.borderOf(context).withValues(alpha: 0.1)
-                  : isRecommended
+                  : isExpanded
-                      ? Colors.green.withValues(alpha: 0.1)
+                      ? RetroColors.panelBgOf(context)
-                      : isExpanded
+                      : Colors.transparent,
-                          ? RetroColors.panelBgOf(context)
-                          : Colors.transparent,
               border: Border(
                 bottom: BorderSide(
                   color: RetroColors.borderOf(context).withValues(alpha: 0.3),
@@ -203,60 +216,127 @@ class _ArenaEquipmentCompareListState extends State<ArenaEquipmentCompareList> {
             ),
             child: Row(
               children: [
-                // 내 장비
+                // 내 장비 (상대가 노리면 빨간 배경)
-                Expanded(child: _buildEquipmentCell(context, myItem, myScore, Colors.blue)),
+                Expanded(
+                  child: _buildEquipmentCell(
+                    context,
+                    myItem,
+                    myScore,
+                    Colors.blue,
+                    isLocked: isLocked,
+                    isTargetedByOpponent: isOpponentTarget,
+                  ),
+                ),
                 // 슬롯 아이콘 (중앙)
-                _buildSlotIndicator(context, slot, isSelected, isRecommended, scoreDiff),
+                _buildSlotIndicator(
-                // 상대 장비
+                  context,
-                Expanded(child: _buildEquipmentCell(context, enemyItem, enemyScore, Colors.red)),
+                  slot,
+                  isSelected,
+                  isRecommended,
+                  scoreDiff,
+                  isLocked: isLocked,
+                  isOpponentTarget: isOpponentTarget,
+                ),
+                // 상대 장비 (내가 선택하거나 추천이면 녹색 배경)
+                Expanded(
+                  child: _buildEquipmentCell(
+                    context,
+                    enemyItem,
+                    enemyScore,
+                    Colors.red,
+                    isLocked: isLocked,
+                    isMyTarget: isMyTarget,
+                    isRecommended: isRecommended && !isMyTarget,
+                  ),
+                ),
               ],
             ),
           ),
         ),
-        // 확장된 비교 패널
+        // 확장된 비교 패널 (잠긴 슬롯은 확장 불가)
-        if (isExpanded)
+        if (isExpanded && !isLocked)
           _buildExpandedPanel(context, slot, myItem, enemyItem, scoreDiff),
       ],
     );
   }
 
   /// 장비 셀 (한쪽)
+  ///
+  /// [isTargetedByOpponent] 상대가 이 슬롯을 노림 (좌측 - 내 장비 손실)
+  /// [isMyTarget] 내가 이 슬롯을 선택함 (우측 - 상대 장비 획득)
+  /// [isRecommended] 추천 슬롯 (우측 - 획득 추천)
   Widget _buildEquipmentCell(
     BuildContext context,
     EquipmentItem? item,
     int score,
-    Color accentColor,
+    Color accentColor, {
-  ) {
+    bool isLocked = false,
+    bool isTargetedByOpponent = false,
+    bool isMyTarget = false,
+    bool isRecommended = false,
+  }) {
     final hasItem = item != null && item.isNotEmpty;
     final rarityColor = hasItem ? _getRarityColor(item.rarity) : Colors.grey;
 
-    return Row(
+    // 배경색 결정
-      children: [
+    Color? bgColor;
-        // 아이템 이름
+    Color? borderColor;
-        Expanded(
+    if (!isLocked) {
-          child: Text(
+      if (isTargetedByOpponent) {
-            hasItem ? item.name : '-',
+        bgColor = Colors.red.withValues(alpha: 0.2); // 손실 예정
+        borderColor = Colors.red.withValues(alpha: 0.5);
+      } else if (isMyTarget) {
+        bgColor = Colors.green.withValues(alpha: 0.25); // 획득 예정
+        borderColor = Colors.green.withValues(alpha: 0.6);
+      } else if (isRecommended) {
+        bgColor = Colors.green.withValues(alpha: 0.15); // 추천
+        borderColor = Colors.green.withValues(alpha: 0.4);
+      }
+    }
+
+    final textColor = isLocked
+        ? RetroColors.textMutedOf(context)
+        : hasItem
+            ? rarityColor
+            : RetroColors.textMutedOf(context);
+
+    return Container(
+      padding: const EdgeInsets.symmetric(horizontal: 6, vertical: 6),
+      decoration: BoxDecoration(
+        color: bgColor,
+        borderRadius: BorderRadius.circular(4),
+        border: borderColor != null ? Border.all(color: borderColor) : null,
+      ),
+      child: Row(
+        children: [
+          // 아이템 이름
+          Expanded(
+            child: Text(
+              hasItem ? item.name : '-',
+              style: TextStyle(
+                fontFamily: 'PressStart2P',
+                fontSize: 6,
+                color: textColor,
+              ),
+              maxLines: 1,
+              overflow: TextOverflow.ellipsis,
+            ),
+          ),
+          // 점수
+          Text(
+            '$score',
             style: TextStyle(
               fontFamily: 'PressStart2P',
-              fontSize: 5,
+              fontSize: 6,
-              color: hasItem ? rarityColor : RetroColors.textMutedOf(context),
+              color: isLocked
+                  ? RetroColors.textMutedOf(context)
+                  : hasItem
+                      ? RetroColors.textSecondaryOf(context)
+                      : RetroColors.textMutedOf(context),
             ),
-            maxLines: 1,
-            overflow: TextOverflow.ellipsis,
           ),
-        ),
+        ],
-        // 점수
+      ),
-        Text(
-          '$score',
-          style: TextStyle(
-            fontFamily: 'PressStart2P',
-            fontSize: 5,
-            color: hasItem
-                ? RetroColors.textSecondaryOf(context)
-                : RetroColors.textMutedOf(context),
-          ),
-        ),
-      ],
     );
   }
 
@@ -266,14 +346,27 @@ class _ArenaEquipmentCompareListState extends State<ArenaEquipmentCompareList> {
     EquipmentSlot slot,
     bool isSelected,
     bool isRecommended,
-    int scoreDiff,
+    int scoreDiff, {
-  ) {
+    bool isLocked = false,
+    bool isOpponentTarget = false,
+  }) {
     final Color borderColor;
     final Color bgColor;
 
-    if (isSelected) {
+    if (isLocked) {
+      borderColor = RetroColors.borderOf(context).withValues(alpha: 0.5);
+      bgColor = RetroColors.borderOf(context).withValues(alpha: 0.1);
+    } else if (isSelected && isOpponentTarget) {
+      // 양쪽 모두 선택 - 금색 테두리 유지
       borderColor = RetroColors.goldOf(context);
       bgColor = RetroColors.goldOf(context).withValues(alpha: 0.3);
+    } else if (isSelected) {
+      borderColor = RetroColors.goldOf(context);
+      bgColor = RetroColors.goldOf(context).withValues(alpha: 0.3);
+    } else if (isOpponentTarget) {
+      // 상대만 선택 - 빨간 표시
+      borderColor = Colors.red.withValues(alpha: 0.7);
+      bgColor = Colors.red.withValues(alpha: 0.15);
     } else if (isRecommended) {
       borderColor = Colors.green;
       bgColor = Colors.green.withValues(alpha: 0.2);
@@ -295,15 +388,27 @@ class _ArenaEquipmentCompareListState extends State<ArenaEquipmentCompareList> {
         children: [
           // 슬롯 아이콘
           Icon(
-            _getSlotIcon(slot),
+            isLocked ? Icons.lock : _getSlotIcon(slot),
             size: 12,
-            color: isSelected
+            color: isLocked
-                ? RetroColors.goldOf(context)
+                ? RetroColors.textMutedOf(context)
-                : RetroColors.textSecondaryOf(context),
+                : isSelected
+                    ? RetroColors.goldOf(context)
+                    : RetroColors.textSecondaryOf(context),
           ),
           const SizedBox(height: 2),
-          // 점수 변화
+          // 잠금 표시 또는 점수 변화
-          _buildScoreDiffBadge(context, scoreDiff, isRecommended),
+          if (isLocked)
+            Text(
+              _weaponLockedLabel,
+              style: TextStyle(
+                fontFamily: 'PressStart2P',
+                fontSize: 4,
+                color: RetroColors.textMutedOf(context),
+              ),
+            )
+          else
+            _buildScoreDiffBadge(context, scoreDiff, isRecommended),
         ],
       ),
     );

lib/src/features/arena/widgets/arena_result_dialog.dart

@@ -33,7 +33,10 @@ class ArenaResultDialog extends StatelessWidget {
   Widget build(BuildContext context) {
     final isVictory = result.isVictory;
     final resultColor = isVictory ? Colors.amber : Colors.red;
-    final slot = result.match.bettingSlot;
+    // 승패에 따라 교환 슬롯 결정
+    final slot = isVictory
+        ? result.match.challengerBettingSlot
+        : result.match.opponentBettingSlot;
 
     return AlertDialog(
       backgroundColor: RetroColors.panelBgOf(context),

lib/src/features/arena/widgets/arena_result_panel.dart

@@ -243,9 +243,15 @@ class _ArenaResultPanelState extends State<ArenaResultPanel>
   }
 
   Widget _buildExchangeSection(BuildContext context) {
-    final slot = widget.result.match.bettingSlot;
     final isVictory = widget.result.isVictory;
 
+    // 승패에 따라 교환 슬롯 결정
+    // 승리: 도전자가 선택한 슬롯(상대에게서 약탈)
+    // 패배: 상대가 선택한 슬롯(도전자에게서 약탈당함)
+    final slot = isVictory
+        ? widget.result.match.challengerBettingSlot
+        : widget.result.match.opponentBettingSlot;
+
     // 도전자의 교환 결과
     final oldItem = _findItem(
       widget.result.match.challenger.finalEquipment,