Refactor screens to MVC architecture with modular widgets

- Extract business logic from screens into dedicated controllers
- Split large screen files into smaller, reusable widget components
- Add controllers for AddSubscriptionScreen and DetailScreen
- Create modular widgets for subscription and detail features
- Improve code organization and maintainability
- Remove duplicated code and improve reusability

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

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

lib/widgets/add_subscription/add_subscription_event_section.dart

@@ -0,0 +1,142 @@
+import 'package:flutter/material.dart';
+import '../../controllers/add_subscription_controller.dart';
+import '../common/form_fields/currency_input_field.dart';
+import '../common/form_fields/date_picker_field.dart';
+
+/// 구독 추가 화면의 이벤트/할인 섹션
+class AddSubscriptionEventSection extends StatelessWidget {
+  final AddSubscriptionController controller;
+  final Animation<double> fadeAnimation;
+  final Animation<Offset> slideAnimation;
+  final Function setState;
+
+  const AddSubscriptionEventSection({
+    super.key,
+    required this.controller,
+    required this.fadeAnimation,
+    required this.slideAnimation,
+    required this.setState,
+  });
+
+  @override
+  Widget build(BuildContext context) {
+    return FadeTransition(
+      opacity: Tween<double>(begin: 0.0, end: 1.0).animate(
+        CurvedAnimation(
+          parent: controller.animationController!,
+          curve: const Interval(0.4, 1.0, curve: Curves.easeIn),
+        ),
+      ),
+      child: SlideTransition(
+        position: Tween<Offset>(
+          begin: const Offset(0.0, 0.5),
+          end: Offset.zero,
+        ).animate(CurvedAnimation(
+          parent: controller.animationController!,
+          curve: const Interval(0.4, 1.0, curve: Curves.easeOutCubic),
+        )),
+        child: Container(
+          margin: const EdgeInsets.only(bottom: 20),
+          padding: const EdgeInsets.all(16),
+          decoration: BoxDecoration(
+            color: Colors.white,
+            borderRadius: BorderRadius.circular(16),
+            border: Border.all(
+              color: controller.isEventActive 
+                  ? const Color(0xFF3B82F6) 
+                  : Colors.grey.withOpacity(0.2),
+              width: controller.isEventActive ? 2 : 1,
+            ),
+          ),
+          child: Column(
+            crossAxisAlignment: CrossAxisAlignment.start,
+            children: [
+              Row(
+                children: [
+                  Checkbox(
+                    value: controller.isEventActive,
+                    onChanged: (value) {
+                      setState(() {
+                        controller.isEventActive = value ?? false;
+                        if (!controller.isEventActive) {
+                          // 이벤트 비활성화 시 관련 데이터 초기화
+                          controller.eventStartDate = DateTime.now();
+                          controller.eventEndDate = DateTime.now().add(const Duration(days: 30));
+                          controller.eventPriceController.clear();
+                        } else {
+                          // 이벤트 활성화 시 날짜가 null이면 기본값 설정
+                          controller.eventStartDate ??= DateTime.now();
+                          controller.eventEndDate ??= DateTime.now().add(const Duration(days: 30));
+                        }
+                      });
+                    },
+                    activeColor: const Color(0xFF3B82F6),
+                  ),
+                  const Text(
+                    '이벤트/할인 설정',
+                    style: TextStyle(
+                      fontSize: 16,
+                      fontWeight: FontWeight.w600,
+                      color: Color(0xFF1E293B),
+                    ),
+                  ),
+                  const SizedBox(width: 8),
+                  Icon(
+                    Icons.local_offer,
+                    size: 20,
+                    color: controller.isEventActive 
+                        ? const Color(0xFF3B82F6)
+                        : Colors.grey,
+                  ),
+                ],
+              ),
+              
+              // 이벤트 활성화 시 추가 필드 표시
+              AnimatedContainer(
+                duration: const Duration(milliseconds: 300),
+                height: controller.isEventActive ? null : 0,
+                child: AnimatedOpacity(
+                  duration: const Duration(milliseconds: 300),
+                  opacity: controller.isEventActive ? 1.0 : 0.0,
+                  child: Column(
+                    children: [
+                      const SizedBox(height: 20),
+                      
+                      // 이벤트 기간
+                      DateRangePickerField(
+                        startDate: controller.eventStartDate,
+                        endDate: controller.eventEndDate,
+                        onStartDateSelected: (date) {
+                          setState(() {
+                            controller.eventStartDate = date;
+                          });
+                        },
+                        onEndDateSelected: (date) {
+                          setState(() {
+                            controller.eventEndDate = date;
+                          });
+                        },
+                        startLabel: '시작일',
+                        endLabel: '종료일',
+                        primaryColor: const Color(0xFF3B82F6),
+                      ),
+                      const SizedBox(height: 20),
+                      
+                      // 이벤트 가격
+                      CurrencyInputField(
+                        controller: controller.eventPriceController,
+                        currency: controller.currency,
+                        label: '이벤트 가격',
+                        hintText: '할인된 가격을 입력하세요',
+                      ),
+                    ],
+                  ),
+                ),
+              ),
+            ],
+          ),
+        ),
+      ),
+    );
+  }
+}