feat(client): 公开商品页改读真实数据，移除茅台 mock 硬编码

- _DescriptionSection: 接受 title/body/keywords 三参数，移除 _mockBody/_mockKeywords 和茅台专属文案
- _ParamsCard: 新增 origin/shelfLife/storage 参数；产地空时不显示，生产日期无时不显示，保质期/储存方式用后端返回值（含默认话术）
- 数据提取段：新增 origin/shelfLife/storage/descriptionTitle/descriptionKeywords 从 API 响应读取
- 删除未使用的 _extractKeywords 方法

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

client/lib/screens/public/public_product_screen.dart

@@ -115,6 +115,13 @@ class _PublicProductScreenState extends State<PublicProductScreen> {
     final brand = d['brand'] as String? ?? '';
     final unit = d['unit'] as String? ?? '';
     final description = d['description'] as String? ?? '';
+    final descriptionTitle = d['description_title'] as String? ?? '商品介绍';
+    final descriptionKeywords = (d['description_keywords'] as List<dynamic>?)
+        ?.map((e) => e as String)
+        .toList() ?? const <String>[];
+    final origin = d['origin'] as String? ?? '';
+    final shelfLife = d['shelf_life'] as String? ?? '无限期（适饮）';
+    final storage = d['storage'] as String? ?? '阴凉干燥、避光保存';
     final shop = d['shop'] as Map<String, dynamic>?;
     final batch = d['batch'] as Map<String, dynamic>?;
     final quickSpecs = _parseQuickSpecs(spec, batch?['production_date'] as String?);
@@ -151,9 +158,13 @@ class _PublicProductScreenState extends State<PublicProductScreen> {
                   SliverToBoxAdapter(
                     child: _QuickSpecs(items: quickSpecs),
                   ),
-                // 5. Description — always shown; falls back to editorial mock text
+                // 5. Description — always shown; body/keywords come from backend (三级回退)
                 SliverToBoxAdapter(
-                  child: _DescriptionSection(description: description),
+                  child: _DescriptionSection(
+                    title: descriptionTitle,
+                    body: description,
+                    keywords: descriptionKeywords,
+                  ),
                 ),
                 // 6. Params — full table
                 SliverToBoxAdapter(
@@ -164,6 +175,9 @@ class _PublicProductScreenState extends State<PublicProductScreen> {
                     series: series,
                     unit: unit,
                     productionDate: productionDate,
+                    origin: origin,
+                    shelfLife: shelfLife,
+                    storage: storage,
                   ),
                 ),
                 // 7. Authenticity card (batch + stamp)
@@ -813,22 +827,17 @@ class _QuickSpecs extends StatelessWidget {
 // ── Description Section ───────────────────────────────────────────────
 
 class _DescriptionSection extends StatelessWidget {
-  final String description;
-  const _DescriptionSection({required this.description});
-
-  static const _mockBody =
-      '飞天牌茅台酒采用本地优质红高粱与小麦为原料，承袭历经数百年沉淀的酱香酿造工艺，'
-      '经一年一个生产周期、两次投料、九次蒸煮、八次发酵、七次取酒，'
-      '于陶坛中陈藏至少五年，方得装瓶。色泽微黄透明，开瓶酱香盈室，'
-      '入口绵柔不烈，咽下后舌底生津，余香萦绕，是中国酱香型白酒之典范。';
-
-  static const _mockKeywords = ['酱香典范', '陈藏五年', '回味悠长', '国家地理标志保护产品'];
+  final String title;
+  final String body;
+  final List<String> keywords;
+  const _DescriptionSection({
+    required this.title,
+    required this.body,
+    required this.keywords,
+  });
 
   @override
   Widget build(BuildContext context) {
-    final body = description.isNotEmpty ? description : _mockBody;
-    final keywords = description.isNotEmpty ? _extractKeywords(description) : _mockKeywords;
-
     return Container(
       padding: const EdgeInsets.fromLTRB(20, 24, 20, 20),
       decoration: const BoxDecoration(
@@ -838,7 +847,7 @@ class _DescriptionSection extends StatelessWidget {
       child: Column(
         crossAxisAlignment: CrossAxisAlignment.start,
         children: [
-          const _SectionHeader(title: '商品介绍'),
+          _SectionHeader(title: title),
           const SizedBox(height: 14),
           Text(
             body,
@@ -865,10 +874,6 @@ class _DescriptionSection extends StatelessWidget {
     );
   }
 
-  List<String> _extractKeywords(String text) {
-    final matches = RegExp(r'【([^】]+)】').allMatches(text);
-    return matches.map((m) => m.group(1)!).toList();
-  }
 }
 
 // ── Authenticity Card ─────────────────────────────────────────────────
@@ -1062,6 +1067,9 @@ class _StampPainter extends CustomPainter {
 class _ParamsCard extends StatelessWidget {
   final String publicId, spec, brand, series, unit;
   final String? productionDate;
+  final String origin;    // 空串表示无产地数据，不显示该行
+  final String shelfLife; // 后端已回填默认值
+  final String storage;   // 后端已回填默认值
   const _ParamsCard({
     required this.publicId,
     required this.spec,
@@ -1069,6 +1077,9 @@ class _ParamsCard extends StatelessWidget {
     required this.series,
     required this.unit,
     this.productionDate,
+    this.origin = '',
+    this.shelfLife = '无限期（适饮）',
+    this.storage = '阴凉干燥、避光保存',
   });
 
   @override
@@ -1086,10 +1097,10 @@ class _ParamsCard extends StatelessWidget {
       if (degM != null) (label: '酒精度', value: '${degM.group(1)!}% vol', mono: false),
       if (mlM != null) (label: '净含量', value: '${mlM.group(1)!} ml', mono: false),
       if (spec.isNotEmpty) (label: '规格', value: spec, mono: false),
-      (label: '产地', value: '贵州省仁怀市茅台镇', mono: false),
-      (label: '生产日期', value: productionDate ?? '2024-01-01', mono: false),
-      (label: '保质期', value: '无限期（适饮）', mono: false),
-      (label: '储存方式', value: '阴凉干燥、避光保存', mono: false),
+      if (origin.isNotEmpty) (label: '产地', value: origin, mono: false),
+      if (productionDate != null) (label: '生产日期', value: productionDate!, mono: false),
+      (label: '保质期', value: shelfLife, mono: false),
+      (label: '储存方式', value: storage, mono: false),
     ];
     if (rows.isEmpty) return const SizedBox.shrink();