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/utils/performance_optimizer.dart

@@ -2,7 +2,6 @@ import 'package:flutter/foundation.dart';
 import 'package:flutter/material.dart';
 import 'package:flutter/scheduler.dart';
 import 'dart:async';
-import 'dart:developer' as developer;
 
 /// 성능 최적화를 위한 유틸리티 클래스
 class PerformanceOptimizer {