feat: 扫码商品详情页重设计 + 宣传主页 + nginx 路由完善

- public_product_screen: 1:1 复刻设计稿，新增商品介绍、批次防伪（自定义圆形印章）、完整商品参数表、门店营业时间、页脚链接
- app_theme: 完整品牌色系（brand/gray/accent/semantic）
- shop model: 新增 business_hours 字段，public 接口同步返回
- nginx: 新增 /product/ → Flutter app 扫码入口，修复 /docs /download html 后缀兼容
- web/: 新增宣传主页、功能页、文档页、扫码 HTML 及设计资源
- app_shell: 界面优化

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

client/lib/screens/shell/app_shell.dart

@@ -591,10 +591,10 @@ class _ShopButton extends StatelessWidget {
         child: const Row(
           mainAxisSize: MainAxisSize.min,
           children: [
-            Icon(Icons.wine_bar, color: Colors.white, size: 22),
-            SizedBox(width: 8),
+            _YanmeiMark(size: 28),
+            SizedBox(width: 10),
             Text(
-              '酒库管理系统',
+              '岩美',
               style: TextStyle(
                   color: Colors.white,
                   fontSize: 18,
@@ -608,6 +608,70 @@ class _ShopButton extends StatelessWidget {
   }
 }
 
+/// Brand mark widget — approximates the 岩美 logo SVG without flutter_svg.
+/// Dark blue rounded rect, white mountain/wave strokes, bordeaux dot.
+class _YanmeiMark extends StatelessWidget {
+  final double size;
+  const _YanmeiMark({this.size = 32});
+
+  @override
+  Widget build(BuildContext context) {
+    return Container(
+      width: size,
+      height: size,
+      decoration: BoxDecoration(
+        color: const Color(0xFF0F3057),
+        borderRadius: BorderRadius.circular(size * 0.19),
+      ),
+      child: CustomPaint(
+        painter: _YanmeiMarkPainter(),
+      ),
+    );
+  }
+}
+
+class _YanmeiMarkPainter extends CustomPainter {
+  @override
+  void paint(Canvas canvas, Size size) {
+    final w = size.width;
+    final h = size.height;
+    final paint = Paint()
+      ..color = Colors.white
+      ..strokeWidth = w * 0.055
+      ..style = PaintingStyle.stroke
+      ..strokeCap = StrokeCap.round
+      ..strokeJoin = StrokeJoin.round;
+
+    // Mountain/wave path: M14 38 L22 22 L32 32 L42 22 L50 38 (on 64px grid)
+    final path = Path();
+    path.moveTo(w * 0.219, h * 0.594);
+    path.lineTo(w * 0.344, h * 0.344);
+    path.lineTo(w * 0.500, h * 0.500);
+    path.lineTo(w * 0.656, h * 0.344);
+    path.lineTo(w * 0.781, h * 0.594);
+    canvas.drawPath(path, paint);
+
+    // Horizontal baseline: M12 46 L52 46 (on 64px grid)
+    canvas.drawLine(
+      Offset(w * 0.1875, h * 0.719),
+      Offset(w * 0.8125, h * 0.719),
+      paint,
+    );
+
+    // Bordeaux dot: circle cx=32 cy=52 r=2.4 (on 64px grid)
+    canvas.drawCircle(
+      Offset(w * 0.500, h * 0.859),
+      w * 0.042,
+      Paint()
+        ..color = const Color(0xFFC97B86)
+        ..style = PaintingStyle.fill,
+    );
+  }
+
+  @override
+  bool shouldRepaint(covariant CustomPainter oldDelegate) => false;
+}
+
 class _InfoRow extends StatelessWidget {
   final IconData icon;
   final String label;