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

- pending_analysis_banner: Colors.orange.* → appColors.warning（グラデーション・影・バッジ）
- activity_stats: Colors.orange → appColors.warning（残回数少ない警告色・テキスト）
- scan_screen: Colors.grey → appColors.textTertiary（蔵元/産地テキスト）
- sake_no_match_state: Colors.grey[400/600] → appColors.textTertiary（空状態アイコン・テキスト）
- camera_screen: Colors.greenAccent → appColors.success（解析開始ボタン）

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

lib/screens/camera_screen.dart

@@ -596,7 +596,7 @@ class _CameraScreenState extends ConsumerState<CameraScreen> with SingleTickerPr
                               IconButton(
                                 icon: Badge(
                                   label: Text('${capturedImages.length}'),
-                                  child: const Icon(LucideIcons.playCircle, color: Colors.greenAccent, size: 40),
+                                  child: Icon(LucideIcons.playCircle, color: appColors.success, size: 40),
                                 ),
                                 onPressed: analyzeImages,
                                 tooltip: '解析を開始',

lib/screens/scan_screen.dart

@@ -395,7 +395,7 @@ class _DigitalSakeCardDialog extends StatelessWidget {
               const SizedBox(height: 8),
               Text(
                 '$brewery / $prefecture',
-                style: const TextStyle(fontSize: 14, color: Colors.grey),
+                style: TextStyle(fontSize: 14, color: appColors.textTertiary),
               ),
                
               const SizedBox(height: 20),

lib/widgets/gamification/activity_stats.dart

@@ -37,7 +37,7 @@ class ActivityStats extends ConsumerWidget {
         final apiColor  = isExhausted
             ? appColors.error
             : isLow
-                ? Colors.orange
+                ? appColors.warning
                 : appColors.brandPrimary;
 
         // Bento Grid: 総登録数を大カード、お気に入り・撮影日数を小カード2枚横並び
@@ -192,7 +192,7 @@ class ActivityStats extends ConsumerWidget {
                     const SizedBox(height: 6),
                     Text(
                       '残り$remaining回です。',
-                      style: const TextStyle(fontSize: 10, color: Colors.orange),
+                      style: TextStyle(fontSize: 10, color: appColors.warning),
                     ),
                   ],
                 ],

lib/widgets/home/sake_no_match_state.dart

@@ -2,19 +2,21 @@ import 'package:flutter/material.dart';
 import 'package:flutter_riverpod/flutter_riverpod.dart';
 import '../../providers/filter_providers.dart';
 import 'package:lucide_icons/lucide_icons.dart';
+import '../../theme/app_colors.dart';
 
 class SakeNoMatchState extends ConsumerWidget {
   const SakeNoMatchState({super.key});
 
   @override
   Widget build(BuildContext context, WidgetRef ref) {
+    final appColors = Theme.of(context).extension<AppColors>()!;
     return Center(
       child: Column(
         mainAxisAlignment: MainAxisAlignment.center,
         children: [
-          Icon(LucideIcons.filterX, size: 48, color: Colors.grey[400]),
+          Icon(LucideIcons.filterX, size: 48, color: appColors.textTertiary),
           const SizedBox(height: 16),
-          Text('条件に一致するお酒が見つかりません', style: TextStyle(color: Colors.grey[600])),
+          Text('条件に一致するお酒が見つかりません', style: TextStyle(color: appColors.textTertiary)),
           TextButton(
             child: const Text('フィルタを解除'),
             onPressed: () {

lib/widgets/pending_analysis_banner.dart

@@ -3,6 +3,7 @@ import 'package:flutter_riverpod/flutter_riverpod.dart';
 import 'package:lucide_icons/lucide_icons.dart';
 import '../services/draft_service.dart';
 import '../screens/pending_analysis_screen.dart';
+import '../theme/app_colors.dart';
 
 /// 未解析Draft（解析待ちアイテム）通知バナー
 ///
@@ -24,19 +25,21 @@ class PendingAnalysisBanner extends ConsumerWidget {
           return const SizedBox.shrink();
         }
 
+        final appColors = Theme.of(context).extension<AppColors>()!;
+
         return Container(
           margin: const EdgeInsets.all(12),
           decoration: BoxDecoration(
             gradient: LinearGradient(
               colors: [
-                Colors.orange.shade600,
-                Colors.orange.shade400,
+                appColors.warning,
+                appColors.warning.withValues(alpha: 0.85),
               ],
             ),
             borderRadius: BorderRadius.circular(12),
             boxShadow: [
               BoxShadow(
-                color: Colors.orange.withValues(alpha: 0.3),
+                color: appColors.warning.withValues(alpha: 0.3),
                 blurRadius: 8,
                 offset: const Offset(0, 2),
               ),
@@ -98,7 +101,7 @@ class PendingAnalysisBanner extends ConsumerWidget {
                                 child: Text(
                                   '$pendingCount件',
                                   style: TextStyle(
-                                    color: Colors.orange.shade700,
+                                    color: appColors.warning,
                                     fontSize: 14,
                                     fontWeight: FontWeight.bold,
                                   ),