feat: adopt material 3 theme and billing adjustments

lib/screens/main_screen.dart

@@ -3,7 +3,8 @@ import 'package:flutter/services.dart';
 import 'package:provider/provider.dart';
 import '../providers/app_lock_provider.dart';
 import '../providers/navigation_provider.dart';
-import '../theme/app_colors.dart';
+// import '../theme/app_colors.dart';
+import '../theme/color_scheme_ext.dart';
 import '../routes/app_routes.dart';
 import 'analysis_screen.dart';
 import 'app_lock_screen.dart';
@@ -11,7 +12,6 @@ import 'settings_screen.dart';
 import 'sms_scan_screen.dart';
 import '../utils/animation_controller_helper.dart';
 import '../widgets/floating_navigation_bar.dart';
-import '../widgets/glassmorphic_scaffold.dart';
 import '../widgets/home_content.dart';
 import '../l10n/app_localizations.dart';
 import '../utils/platform_helper.dart';
@@ -162,33 +162,34 @@ class _MainScreenState extends State<MainScreen>
       if (result == true) {
         // 상단에 스낵바 표시
         if (!context.mounted) return;
+        final cs = Theme.of(context).colorScheme;
         ScaffoldMessenger.of(context).showSnackBar(
           SnackBar(
             content: Row(
               children: [
-                const Icon(
+                Icon(
                   Icons.check_circle,
-                  color: AppColors.pureWhite,
+                  color: cs.onPrimary,
                   size: 20,
                 ),
                 const SizedBox(width: 12),
                 Text(
                   AppLocalizations.of(context).subscriptionAdded,
-                  style: const TextStyle(
+                  style: TextStyle(
                     fontSize: 16,
                     fontWeight: FontWeight.w500,
-                    color: AppColors.pureWhite,
+                    color: cs.onPrimary,
                   ),
                 ),
               ],
             ),
-            backgroundColor: AppColors.successColor,
+            backgroundColor: cs.success,
             behavior: SnackBarBehavior.floating,
             margin: EdgeInsets.only(
-              top: MediaQuery.of(context).padding.top + 8, // 더 상단으로
+              top: MediaQuery.of(context).padding.top + 8,
               left: 16,
               right: 16,
-              bottom: MediaQuery.of(context).size.height - 100, // 더 상단으로
+              bottom: MediaQuery.of(context).size.height - 100,
             ),
             shape: RoundedRectangleBorder(
               borderRadius: BorderRadius.circular(12),
@@ -223,8 +224,7 @@ class _MainScreenState extends State<MainScreen>
   Widget build(BuildContext context) {
     final navigationProvider = context.watch<NavigationProvider>();
 
-    // 메인 그라데이션 사용
-    List<Color> backgroundGradient = AppColors.mainGradient;
+    // 그라데이션 제거: 단색 배경 사용
 
     // 현재 인덱스가 유효한지 확인
     int currentIndex = navigationProvider.currentIndex;
@@ -232,25 +232,31 @@ class _MainScreenState extends State<MainScreen>
       currentIndex = 0; // 추가 버튼은 홈으로 표시
     }
 
-    return GlassmorphicScaffold(
-      body: IndexedStack(
-        index: PlatformHelper.isIOS
-            ? (currentIndex == 3 ? 3 : currentIndex) // iOS: 설정화면은 인덱스 3
-            : (currentIndex == 3
-                ? 3
-                : currentIndex == 4
-                    ? 4
-                    : currentIndex), // Android: 기존 로직
-        children: _screens,
-      ),
-      backgroundGradient: backgroundGradient,
-      useFloatingNavBar: true,
-      floatingNavBarIndex: navigationProvider.currentIndex,
-      onFloatingNavBarTapped: (index) {
-        _handleNavigation(index, context);
-      },
-      enableParticles: false,
-      enableWaveAnimation: false,
+    return Stack(
+      children: [
+        Positioned.fill(
+          child: Container(color: Theme.of(context).colorScheme.surface),
+        ),
+        Scaffold(
+          extendBody: true,
+          extendBodyBehindAppBar: true,
+          body: IndexedStack(
+            index: PlatformHelper.isIOS
+                ? (currentIndex == 3 ? 3 : currentIndex) // iOS: 설정화면은 인덱스 3
+                : (currentIndex == 3
+                    ? 3
+                    : currentIndex == 4
+                        ? 4
+                        : currentIndex), // Android: 기존 로직
+            children: _screens,
+          ),
+        ),
+        FloatingNavigationBar(
+          selectedIndex: navigationProvider.currentIndex,
+          isVisible: true,
+          onItemTapped: (index) => _handleNavigation(index, context),
+        ),
+      ],
     );
   }
 }