feat: 라이선스 관리 기능 개선 및 폼 검증 강화

- LicenseDto 모델 업데이트
- 라이선스 폼 UI 개선 및 검증 로직 강화
- 라이선스 리스트 화면 필터링 기능 추가
- 만료일 관리 기능 개선

🤖 Generated with [Claude Code](https://claude.ai/code)

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

lib/data/models/license/license_dto.dart

@@ -25,6 +25,27 @@ DateTime? _dateFromJson(String? dateStr) {
   }
 }
 
+// 문자열이나 숫자를 double로 변환하는 헬퍼 함수
+double? _priceFromJson(dynamic value) {
+  if (value == null) return null;
+  if (value is double) return value;
+  if (value is int) return value.toDouble();
+  if (value is String) {
+    try {
+      return double.parse(value);
+    } catch (e) {
+      return null;
+    }
+  }
+  return null;
+}
+
+// double을 문자열로 변환하는 헬퍼 함수
+String? _priceToJson(double? value) {
+  if (value == null) return null;
+  return value.toStringAsFixed(2);
+}
+
 // 필수 날짜 필드용 헬퍼 함수 (항상 non-null DateTime 반환)
 DateTime _requiredDateFromJson(String? dateStr) {
   if (dateStr == null || dateStr.isEmpty) return DateTime.now();
@@ -53,7 +74,7 @@ class LicenseDto with _$LicenseDto {
     @JsonKey(name: 'user_count') int? userCount,
     @JsonKey(name: 'purchase_date', toJson: _dateToJson, fromJson: _dateFromJson) DateTime? purchaseDate,
     @JsonKey(name: 'expiry_date', toJson: _dateToJson, fromJson: _dateFromJson) DateTime? expiryDate,
-    @JsonKey(name: 'purchase_price') double? purchasePrice,
+    @JsonKey(name: 'purchase_price', toJson: _priceToJson, fromJson: _priceFromJson) double? purchasePrice,
     @JsonKey(name: 'company_id') int? companyId,
     @JsonKey(name: 'branch_id') int? branchId,
     @JsonKey(name: 'assigned_user_id') int? assignedUserId,

lib/data/models/license/license_dto.freezed.dart

@@ -34,7 +34,8 @@ mixin _$LicenseDto {
   DateTime? get purchaseDate => throw _privateConstructorUsedError;
   @JsonKey(name: 'expiry_date', toJson: _dateToJson, fromJson: _dateFromJson)
   DateTime? get expiryDate => throw _privateConstructorUsedError;
-  @JsonKey(name: 'purchase_price')
+  @JsonKey(
+      name: 'purchase_price', toJson: _priceToJson, fromJson: _priceFromJson)
   double? get purchasePrice => throw _privateConstructorUsedError;
   @JsonKey(name: 'company_id')
   int? get companyId => throw _privateConstructorUsedError;
@@ -86,7 +87,11 @@ abstract class $LicenseDtoCopyWith<$Res> {
       @JsonKey(
           name: 'expiry_date', toJson: _dateToJson, fromJson: _dateFromJson)
       DateTime? expiryDate,
-      @JsonKey(name: 'purchase_price') double? purchasePrice,
+      @JsonKey(
+          name: 'purchase_price',
+          toJson: _priceToJson,
+          fromJson: _priceFromJson)
+      double? purchasePrice,
       @JsonKey(name: 'company_id') int? companyId,
       @JsonKey(name: 'branch_id') int? branchId,
       @JsonKey(name: 'assigned_user_id') int? assignedUserId,
@@ -236,7 +241,11 @@ abstract class _$$LicenseDtoImplCopyWith<$Res>
       @JsonKey(
           name: 'expiry_date', toJson: _dateToJson, fromJson: _dateFromJson)
       DateTime? expiryDate,
-      @JsonKey(name: 'purchase_price') double? purchasePrice,
+      @JsonKey(
+          name: 'purchase_price',
+          toJson: _priceToJson,
+          fromJson: _priceFromJson)
+      double? purchasePrice,
       @JsonKey(name: 'company_id') int? companyId,
       @JsonKey(name: 'branch_id') int? branchId,
       @JsonKey(name: 'assigned_user_id') int? assignedUserId,
@@ -379,7 +388,11 @@ class _$LicenseDtoImpl implements _LicenseDto {
       @JsonKey(
           name: 'expiry_date', toJson: _dateToJson, fromJson: _dateFromJson)
       this.expiryDate,
-      @JsonKey(name: 'purchase_price') this.purchasePrice,
+      @JsonKey(
+          name: 'purchase_price',
+          toJson: _priceToJson,
+          fromJson: _priceFromJson)
+      this.purchasePrice,
       @JsonKey(name: 'company_id') this.companyId,
       @JsonKey(name: 'branch_id') this.branchId,
       @JsonKey(name: 'assigned_user_id') this.assignedUserId,
@@ -417,7 +430,8 @@ class _$LicenseDtoImpl implements _LicenseDto {
   @JsonKey(name: 'expiry_date', toJson: _dateToJson, fromJson: _dateFromJson)
   final DateTime? expiryDate;
   @override
-  @JsonKey(name: 'purchase_price')
+  @JsonKey(
+      name: 'purchase_price', toJson: _priceToJson, fromJson: _priceFromJson)
   final double? purchasePrice;
   @override
   @JsonKey(name: 'company_id')
@@ -552,7 +566,11 @@ abstract class _LicenseDto implements LicenseDto {
       @JsonKey(
           name: 'expiry_date', toJson: _dateToJson, fromJson: _dateFromJson)
       final DateTime? expiryDate,
-      @JsonKey(name: 'purchase_price') final double? purchasePrice,
+      @JsonKey(
+          name: 'purchase_price',
+          toJson: _priceToJson,
+          fromJson: _priceFromJson)
+      final double? purchasePrice,
       @JsonKey(name: 'company_id') final int? companyId,
       @JsonKey(name: 'branch_id') final int? branchId,
       @JsonKey(name: 'assigned_user_id') final int? assignedUserId,
@@ -591,7 +609,8 @@ abstract class _LicenseDto implements LicenseDto {
   @JsonKey(name: 'expiry_date', toJson: _dateToJson, fromJson: _dateFromJson)
   DateTime? get expiryDate;
   @override
-  @JsonKey(name: 'purchase_price')
+  @JsonKey(
+      name: 'purchase_price', toJson: _priceToJson, fromJson: _priceFromJson)
   double? get purchasePrice;
   @override
   @JsonKey(name: 'company_id')

lib/data/models/license/license_dto.g.dart

@@ -16,7 +16,7 @@ _$LicenseDtoImpl _$$LicenseDtoImplFromJson(Map<String, dynamic> json) =>
       userCount: (json['user_count'] as num?)?.toInt(),
       purchaseDate: _dateFromJson(json['purchase_date'] as String?),
       expiryDate: _dateFromJson(json['expiry_date'] as String?),
-      purchasePrice: (json['purchase_price'] as num?)?.toDouble(),
+      purchasePrice: _priceFromJson(json['purchase_price']),
       companyId: (json['company_id'] as num?)?.toInt(),
       branchId: (json['branch_id'] as num?)?.toInt(),
       assignedUserId: (json['assigned_user_id'] as num?)?.toInt(),
@@ -39,7 +39,7 @@ Map<String, dynamic> _$$LicenseDtoImplToJson(_$LicenseDtoImpl instance) =>
       'user_count': instance.userCount,
       'purchase_date': _dateToJson(instance.purchaseDate),
       'expiry_date': _dateToJson(instance.expiryDate),
-      'purchase_price': instance.purchasePrice,
+      'purchase_price': _priceToJson(instance.purchasePrice),
       'company_id': instance.companyId,
       'branch_id': instance.branchId,
       'assigned_user_id': instance.assignedUserId,