refactor(model): SpellBook을 SkillBook으로 리네이밍

- 게임 컨셉에 맞게 주문서 → 스킬북 용어 통일
- 관련 모든 참조 일괄 변경

lib/src/features/game/game_play_screen.dart

@@ -366,7 +366,7 @@ class _GamePlayScreenState extends State<GamePlayScreen>
               )
             : (
                 game_l10n.combatSkillDamage(skillName, event.damage),
-                CombatLogType.spell,
+                CombatLogType.skill,
               ),
       CombatEventType.playerHeal => (
         game_l10n.combatSkillHeal(
@@ -1327,11 +1327,11 @@ class _GamePlayScreenState extends State<GamePlayScreen>
     );
   }
 
-  /// 통합 스킬 목록 (SpellBook 기반)
+  /// 통합 스킬 목록 (SkillBook 기반)
   ///
-  /// 스펠 이름, 랭크, 스킬 타입, 쿨타임 표시
+  /// 스킬 이름, 랭크, 스킬 타입, 쿨타임 표시
   Widget _buildSkillsList(GameState state) {
-    if (state.spellBook.spells.isEmpty) {
+    if (state.skillBook.skills.isEmpty) {
       return Center(
         child: Text(
           L10n.of(context).noSpellsYet,
@@ -1345,12 +1345,12 @@ class _GamePlayScreenState extends State<GamePlayScreen>
     }
 
     return ListView.builder(
-      itemCount: state.spellBook.spells.length,
+      itemCount: state.skillBook.skills.length,
       padding: const EdgeInsets.symmetric(horizontal: 8),
       itemBuilder: (context, index) {
-        final spell = state.spellBook.spells[index];
-        final skill = SkillData.getSkillBySpellName(spell.name);
-        final spellName = GameDataL10n.getSpellName(context, spell.name);
+        final skillEntry = state.skillBook.skills[index];
+        final skill = SkillData.getSkillBySpellName(skillEntry.name);
+        final skillName = GameDataL10n.getSpellName(context, skillEntry.name);
 
         // 쿨타임 상태 확인
         final skillState = skill != null
@@ -1361,8 +1361,8 @@ class _GamePlayScreenState extends State<GamePlayScreen>
             !skillState.isReady(state.skillSystem.elapsedMs, skill!.cooldownMs);
 
         return _SkillRow(
-          spellName: spellName,
-          rank: spell.rank,
+          skillName: skillName,
+          rank: skillEntry.rank,
           skill: skill,
           isOnCooldown: isOnCooldown,
         );
@@ -1615,16 +1615,16 @@ class _GamePlayScreenState extends State<GamePlayScreen>
 
 /// 스킬 행 위젯
 ///
-/// 스펠 이름, 랭크, 스킬 타입 아이콘, 쿨타임 상태 표시
+/// 스킬 이름, 랭크, 스킬 타입 아이콘, 쿨타임 상태 표시
 class _SkillRow extends StatelessWidget {
   const _SkillRow({
-    required this.spellName,
+    required this.skillName,
     required this.rank,
     required this.skill,
     required this.isOnCooldown,
   });
 
-  final String spellName;
+  final String skillName;
   final String rank;
   final Skill? skill;
   final bool isOnCooldown;
@@ -1641,7 +1641,7 @@ class _SkillRow extends StatelessWidget {
           // 스킬 이름
           Expanded(
             child: Text(
-              spellName,
+              skillName,
               style: TextStyle(
                 fontSize: 11,
                 color: isOnCooldown ? Colors.grey : null,