Initial commit: SubManager Flutter App

주요 구현 완료 기능:
- 구독 관리 (추가/편집/삭제/카테고리 분류)
- 이벤트 할인 시스템 (기본값 자동 설정)
- SMS 자동 스캔 및 구독 정보 추출
- 알림 시스템 (타임존 처리 안정화)
- 환율 변환 지원 (KRW/USD)
- 반응형 UI 및 애니메이션
- 다국어 지원 (한국어/영어)

버그 수정:
- NotificationService tz.local 초기화 오류 해결
- MainScreenSummaryCard 레이아웃 오버플로우 수정
- 구독 추가 시 LateInitializationError 완전 해결

🤖 Generated with Claude Code

Co-Authored-By: Claude <noreply@anthropic.com>

lib/models/subscription.dart

@@ -0,0 +1,64 @@
+class Subscription {
+  final String id;
+  final String serviceName;
+  final double monthlyCost;
+  final String billingCycle;
+  final DateTime nextBillingDate;
+  final String? category;
+  final String? notes;
+  final int repeatCount;
+  final DateTime? lastPaymentDate;
+  final String? websiteUrl;
+  final String currency;
+
+  Subscription({
+    required this.id,
+    required this.serviceName,
+    required this.monthlyCost,
+    required this.billingCycle,
+    required this.nextBillingDate,
+    this.category,
+    this.notes,
+    this.repeatCount = 1,
+    this.lastPaymentDate,
+    this.websiteUrl,
+    this.currency = 'KRW',
+  });
+
+  Map<String, dynamic> toMap() {
+    return {
+      'id': id,
+      'serviceName': serviceName,
+      'monthlyCost': monthlyCost,
+      'billingCycle': billingCycle,
+      'nextBillingDate': nextBillingDate.toIso8601String(),
+      'category': category,
+      'notes': notes,
+      'repeatCount': repeatCount,
+      'lastPaymentDate': lastPaymentDate?.toIso8601String(),
+      'websiteUrl': websiteUrl,
+      'currency': currency,
+    };
+  }
+
+  factory Subscription.fromMap(Map<String, dynamic> map) {
+    return Subscription(
+      id: map['id'] as String,
+      serviceName: map['serviceName'] as String,
+      monthlyCost: map['monthlyCost'] as double,
+      billingCycle: map['billingCycle'] as String,
+      nextBillingDate: DateTime.parse(map['nextBillingDate'] as String),
+      category: map['category'] as String?,
+      notes: map['notes'] as String?,
+      repeatCount: (map['repeatCount'] as num?)?.toInt() ?? 1,
+      lastPaymentDate: map['lastPaymentDate'] != null
+          ? DateTime.parse(map['lastPaymentDate'] as String)
+          : null,
+      websiteUrl: map['websiteUrl'] as String?,
+      currency: map['currency'] as String? ?? 'KRW',
+    );
+  }
+
+  // 주기적 결제 여부 확인
+  bool get isRecurring => repeatCount > 1;
+}