refactor: ハードコード色をAppColorsセマンティックカラーに置換

意図的な箇所（カメラUI・AppBar白テキスト・ハート色・Proバッジ等）はKEEP。
以下のUIロジックに影響しない7ファイルのみ変更:

- Colors.grey.shade400/[400] → appColors.iconSubtle (アイコン、無効状態)
- Colors.grey.shade300 → appColors.divider (プレースホルダー背景)
- Colors.grey → appColors.textSecondary / iconSubtle / divider (文脈別)
- Colors.grey[200] → appColors.surfaceSubtle (プログレスバー背景)
- Colors.orange → appColors.warning (警告スナックバー)
- Colors.green / Colors.red → appColors.success / error (完了・失敗スナックバー)

_createBackup()にappColorsをasync前にキャプチャするFlutterベストプラクティスを適用。
コメント化されていたデッドコメントも同時削除。

https://claude.ai/code/session_01DWQpnqrQWwxVKKWSL9kDPp

lib/screens/home_screen.dart

@@ -184,11 +184,11 @@ class HomeScreen extends ConsumerWidget {
                           child: Column(
                             mainAxisAlignment: MainAxisAlignment.center,
                             children: [
-                              Icon(LucideIcons.clipboardCheck, size: 60, color: Colors.grey[400]),
+                              Icon(LucideIcons.clipboardCheck, size: 60, color: appColors.iconSubtle),
                               const SizedBox(height: 16),
                               Text(t['noMenuItems'], style: const TextStyle(fontWeight: FontWeight.bold)),
                               const SizedBox(height: 8),
-                              Text(t['goBackToList'], textAlign: TextAlign.center, style: const TextStyle(color: Colors.grey)),
+                              Text(t['goBackToList'], textAlign: TextAlign.center, style: TextStyle(color: appColors.textSecondary)),
                             ],
                           ),
                         );

lib/screens/main_screen.dart

@@ -65,7 +65,7 @@ class _MainScreenState extends ConsumerState<MainScreen> {
           clipBehavior: Clip.none,
           alignment: Alignment.center,
           children: [
-            Icon(featureIcon, size: 48, color: Colors.grey.shade400),
+            Icon(featureIcon, size: 48, color: appColors.iconSubtle),
             Positioned(
               right: -8,
               top: -8,

lib/screens/menu_pricing_screen.dart

@@ -123,7 +123,7 @@ class _MenuPricingScreenState extends ConsumerState<MenuPricingScreen> {
           preferredSize: const Size.fromHeight(2),
           child: LinearProgressIndicator(
             value: 2 / 3, // Step 2 of 3 = 66%
-            backgroundColor: Colors.grey[200],
+            backgroundColor: Theme.of(context).extension<AppColors>()!.surfaceSubtle,
             valueColor: AlwaysStoppedAnimation<Color>(Theme.of(context).primaryColor),
             minHeight: 2,
           ),
@@ -320,9 +320,9 @@ class _MenuPricingScreenState extends ConsumerState<MenuPricingScreen> {
                    // Drag Handle
                   ReorderableDragStartListener(
                     index: index,
-                    child: const Padding(
-                      padding: EdgeInsets.only(right: 12, top: 4, bottom: 4),
-                      child: Icon(Icons.drag_indicator, color: Colors.grey),
+                    child: Padding(
+                      padding: const EdgeInsets.only(right: 12, top: 4, bottom: 4),
+                      child: Icon(Icons.drag_indicator, color: appColors.iconSubtle),
                     ),
                   ),
                   Expanded(

lib/screens/pending_analysis_screen.dart

@@ -344,10 +344,10 @@ class _PendingAnalysisScreenState extends ConsumerState<PendingAnalysisScreen> {
                                           width: 60,
                                           height: 60,
                                           decoration: BoxDecoration(
-                                            color: Colors.grey.shade300,
+                                            color: appColors.divider,
                                             borderRadius: BorderRadius.circular(8),
                                           ),
-                                          child: const Icon(LucideIcons.image, color: Colors.grey),
+                                          child: Icon(LucideIcons.image, color: appColors.iconSubtle),
                                         ),
                                   title: const Text(
                                     '解析待ち',
@@ -390,7 +390,7 @@ class _PendingAnalysisScreenState extends ConsumerState<PendingAnalysisScreen> {
                                   style: ElevatedButton.styleFrom(
                                     backgroundColor: appColors.brandPrimary,
                                     foregroundColor: Colors.white,
-                                    disabledBackgroundColor: Colors.grey.shade400,
+                                    disabledBackgroundColor: appColors.textTertiary,
                                     shape: RoundedRectangleBorder(
                                       borderRadius: BorderRadius.circular(12),
                                     ),

lib/widgets/map/prefecture_tile_map.dart

@@ -76,7 +76,7 @@ class PrefectureTileMap extends ConsumerWidget {
       if (v.contains(prefName)) prefId = k;
     });
     final regionId = JapanMapData.getRegionId(prefId);
-    final regionColor = regionColors[regionId] ?? Colors.grey;
+    final regionColor = regionColors[regionId] ?? appColors.divider;
 
     Color baseColor;
     Color textColor;

lib/widgets/sake_detail/sake_detail_specs.dart

@@ -75,9 +75,9 @@ class _SakeDetailSpecsState extends State<SakeDetailSpecs> {
       if (_isEditing) {
         // Warn user about external update while editing
         ScaffoldMessenger.of(context).showSnackBar(
-          const SnackBar(
-            content: Text('データが外部から更新されました。編集をキャンセルして再度お試しください。'),
-            backgroundColor: Colors.orange,
+          SnackBar(
+            content: const Text('データが外部から更新されました。編集をキャンセルして再度お試しください。'),
+            backgroundColor: Theme.of(context).extension<AppColors>()!.warning,
           ),
         );
         _cancel(); // Force exit edit mode

lib/widgets/settings/backup_settings_section.dart

@@ -86,6 +86,7 @@ enum _BackupState { idle, signingIn, signingOut, backingUp, restoring }
 
    Future<void> _createBackup() async {
      final messenger = ScaffoldMessenger.of(context);
+     final appColors = Theme.of(context).extension<AppColors>()!;
      setState(() => _state = _BackupState.backingUp);
      final success = await _backupService.createBackup();
      if (mounted) {
@@ -93,11 +94,7 @@ enum _BackupState { idle, signingIn, signingOut, backingUp, restoring }
        messenger.showSnackBar(
          SnackBar(
            content: Text(success ? 'バックアップが完了しました' : 'バックアップに失敗しました'),
-           // Snackbars can keep Green/Red for semantic clarity, or be neutral. 
-           // User asked to remove Green/Red icons from the UI, but feedback (Snackbar) usually stays semantic.
-           // However, to be safe and "Washi", let's use Sumi (Black) for success? 
-           // Or just leave snackbars as they are ephemeral. The request was likely about the visible static UI.
-           backgroundColor: success ? Colors.green : Colors.red,
+           backgroundColor: success ? appColors.success : appColors.error,
          ),
        );
      }
@@ -184,7 +181,7 @@ enum _BackupState { idle, signingIn, signingOut, backingUp, restoring }
          messenger.showSnackBar(
            SnackBar(
              content: Text(success ? '復元が完了しました' : '復元に失敗しました'),
-             backgroundColor: success ? Colors.green : Colors.red,
+             backgroundColor: success ? appColors.success : appColors.error,
            ),
          );
        }