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/main_summary_card.dart

@@ -1,9 +1,7 @@
 import 'package:flutter/material.dart';
-import 'package:flutter/services.dart';
 import 'package:intl/intl.dart';
 import '../providers/subscription_provider.dart';
 import '../theme/app_colors.dart';
-import '../utils/format_helper.dart';
 import 'animated_wave_background.dart';
 import 'glassmorphism_card.dart';