refactor: 타입 안전성 개선 및 하드코딩 문자열 l10n 적용

- return_rewards_dialog: _getRarityColor(dynamic) → ItemRarity? 타입 명시
- stats_section: 하드코딩된 Undo/Rolls 문자열을 l10n으로 교체
- game_text_l10n: uiUndoAndRolls, uiRollsOnly 추가 (한/영/일)
- skill_data: 주석 스킬 개수 70→68 수정

lib/src/features/new_character/widgets/stats_section.dart

@@ -1,5 +1,6 @@
 import 'package:flutter/material.dart';
 
+import 'package:asciineverdie/data/game_text_l10n.dart' as game_l10n;
 import 'package:asciineverdie/l10n/app_localizations.dart';
 import 'package:asciineverdie/src/core/engine/iap_service.dart';
 import 'package:asciineverdie/src/shared/retro_colors.dart';
@@ -141,8 +142,8 @@ class StatsSection extends StatelessWidget {
             child: Center(
               child: Text(
                 canUndo
-                    ? 'Undo: $availableUndos  |  Rolls: $rollsRemaining/5'
-                    : 'Rolls: $rollsRemaining/5',
+                    ? game_l10n.uiUndoAndRolls(availableUndos, rollsRemaining)
+                    : game_l10n.uiRollsOnly(rollsRemaining),
                 style: const TextStyle(
                   fontFamily: 'PressStart2P',
                   fontSize: 11,