feat: API 통합 2차 작업 완료

- 자동 로그인 구현: 앱 시작 시 토큰 확인 후 적절한 화면으로 라우팅
- AuthInterceptor 개선: AuthService와 통합하여 토큰 관리 일원화
- 로그아웃 기능 개선: AuthService를 사용한 API 로그아웃 처리
- 대시보드 API 연동: MockDataService에서 실제 API로 완전 전환
  - Dashboard DTO 모델 생성 (OverviewStats, RecentActivity 등)
  - DashboardRemoteDataSource 및 DashboardService 구현
  - OverviewController를 ChangeNotifier 패턴으로 개선
  - OverviewScreenRedesign에 Provider 패턴 적용
- API 통합 진행 상황 문서 업데이트

lib/data/models/dashboard/overview_stats.g.dart

@@ -0,0 +1,35 @@
+// GENERATED CODE - DO NOT MODIFY BY HAND
+
+part of 'overview_stats.dart';
+
+// **************************************************************************
+// JsonSerializableGenerator
+// **************************************************************************
+
+_$OverviewStatsImpl _$$OverviewStatsImplFromJson(Map<String, dynamic> json) =>
+    _$OverviewStatsImpl(
+      totalEquipment: (json['total_equipment'] as num).toInt(),
+      availableEquipment: (json['available_equipment'] as num).toInt(),
+      inUseEquipment: (json['in_use_equipment'] as num).toInt(),
+      maintenanceEquipment: (json['maintenance_equipment'] as num).toInt(),
+      totalCompanies: (json['total_companies'] as num).toInt(),
+      totalUsers: (json['total_users'] as num).toInt(),
+      activeLicenses: (json['active_licenses'] as num).toInt(),
+      expiringLicenses: (json['expiring_licenses'] as num).toInt(),
+      totalRentals: (json['total_rentals'] as num).toInt(),
+      activeRentals: (json['active_rentals'] as num).toInt(),
+    );
+
+Map<String, dynamic> _$$OverviewStatsImplToJson(_$OverviewStatsImpl instance) =>
+    <String, dynamic>{
+      'total_equipment': instance.totalEquipment,
+      'available_equipment': instance.availableEquipment,
+      'in_use_equipment': instance.inUseEquipment,
+      'maintenance_equipment': instance.maintenanceEquipment,
+      'total_companies': instance.totalCompanies,
+      'total_users': instance.totalUsers,
+      'active_licenses': instance.activeLicenses,
+      'expiring_licenses': instance.expiringLicenses,
+      'total_rentals': instance.totalRentals,
+      'active_rentals': instance.activeRentals,
+    };