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/swipeable_subscription_card.dart

@@ -1,6 +1,4 @@
 import 'package:flutter/material.dart';
-import 'package:flutter/services.dart';
-import 'dart:math' as math;
 import '../models/subscription_model.dart';
 import '../utils/haptic_feedback_helper.dart';
 import 'subscription_card.dart';