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/glassmorphic_scaffold.dart

@@ -2,7 +2,6 @@ import 'package:flutter/material.dart';
 import 'package:flutter/rendering.dart';
 import 'dart:math' as math;
 import '../theme/app_colors.dart';
-import 'glassmorphic_app_bar.dart';
 import 'floating_navigation_bar.dart';
 
 /// 글래스모피즘 디자인이 적용된 통일된 스캐폴드
@@ -79,7 +78,6 @@ class _GlassmorphicScaffoldState extends State<GlassmorphicScaffold>
   void _setupScrollListener() {
     _scrollController?.addListener(() {
       final currentScroll = _scrollController!.position.pixels;
-      final maxScroll = _scrollController!.position.maxScrollExtent;
       
       // 스크롤 방향에 따라 플로팅 네비게이션 바 표시/숨김
       if (currentScroll > 50 && _scrollController!.position.userScrollDirection == ScrollDirection.reverse) {