feat: 商品详情页、XLS导入修复、分页选择器、导出功能

后端：
- 新增 product_images 表，支持每商品最多5张图（服务端压缩至1200px/JPEG85%）
- products 表新增 public_id(UUID)、description 字段
- 新增商品详情接口、二维码接口、公开商品接口（无鉴权）
- 修复 XLS 导入：OLE2 magic bytes 检测 + 临时文件解析，兼容 extrame/xls
- 修复商品/名称/系列/规格三张表导入数据为0（LastCol()=0 bug）
- 所有导入接口返回 total/imported/skipped 统计
- config 新增 StorageConfig，支持 STORAGE_* 环境变量覆盖
- 种子数据修复：products 补 public_id、新增 product_images TRUNCATE、schema.sql 表名修正

前端：
- 商品详情页：图片上传/删除、描述内联编辑、二维码弹窗、公开链接复制
- 公开商品页：无鉴权路由 /product/:public_id，Flutter Web SPA
- 商品详情列表（批次追踪）商品名超链接跳转详情页
- 导航「商品管理」改名「商品详情」
- 所有列表表格新增每页条数选择（10/20/50/100）
- 表格列头内嵌筛选（FilterableColumnHeader）
- 导出 Excel 功能（入库/出库/库存/财务/批次/往来单位）
- 网络恢复自动刷新 + 离线缓存展示

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

client/lib/screens/inventory/batch_tracking_screen.dart

@@ -1,11 +1,13 @@
 import 'package:flutter/material.dart';
 import 'package:flutter_riverpod/flutter_riverpod.dart';
+import 'package:go_router/go_router.dart';
 import '../../core/theme/app_theme.dart';
 import '../../models/inventory.dart';
 import '../../providers/inventory_provider.dart';
 import '../../widgets/data_table_card.dart';
 import '../../widgets/multi_select_dropdown.dart' show ColDef, ColumnToggleButton, FilterableColumnHeader;
 import '../../providers/connectivity_provider.dart';
+import '../../core/utils/export_util.dart';
 
 class BatchTrackingScreen extends ConsumerStatefulWidget {
   const BatchTrackingScreen({super.key});
@@ -17,6 +19,7 @@ class BatchTrackingScreen extends ConsumerStatefulWidget {
 
 class _BatchTrackingScreenState extends ConsumerState<BatchTrackingScreen> {
   int _page = 1;
+  int _pageSize = 20;
   int _total = 0;
   late Future<List<ProductTrackingRecord>> _future;
   List<ProductTrackingRecord> _records = [];
@@ -49,7 +52,7 @@ class _BatchTrackingScreenState extends ConsumerState<BatchTrackingScreen> {
   void _fetch() {
     _future = ref
         .read(inventoryRepositoryProvider)
-        .listProducts(page: _page, pageSize: 20)
+        .listProducts(page: _page, pageSize: _pageSize)
         .then((r) {
       _total = r.total;
       _records = r.data;
@@ -189,15 +192,44 @@ class _BatchTrackingScreenState extends ConsumerState<BatchTrackingScreen> {
     return DataTableCard(
       totalCount: _total,
       page: _page,
+      pageSize: _pageSize,
       onPageChanged: (p) => setState(() {
         _page = p;
         _fetch();
       }),
+      onPageSizeChanged: (s) => setState(() {
+        _pageSize = s;
+        _page = 1;
+        _fetch();
+      }),
       toolbar: Row(
         children: [
           const Text('已审核入库商品（含库存与销售状态）',
               style: TextStyle(fontSize: 13, color: AppTheme.textSecondary)),
           const Spacer(),
+          OutlinedButton.icon(
+            onPressed: () => exportExcel(
+              filename: '商品管理',
+              headers: ['商品名称', '商品编码', '规格', '批次号', '入库单号', '供应商', '仓库', '入库日期', '数量', '单价', '状态', '买家'],
+              rows: records.map((r) => [
+                r.productName ?? '',
+                r.productCode ?? '',
+                r.productSpec ?? '',
+                r.batchNo ?? '',
+                r.orderNo ?? '',
+                r.supplierName ?? '',
+                r.warehouseName ?? '',
+                r.orderDate?.substring(0, 10) ?? '',
+                r.quantity.toInt(),
+                r.unitPrice,
+                r.isSoldOut ? '已卖出' : '在售',
+                r.buyerName ?? '',
+              ]).toList(),
+            ),
+            icon: const Icon(Icons.download, size: 16),
+            label: const Text('导出'),
+          ),
+          const SizedBox(width: 4),
           IconButton(
             icon: const Icon(Icons.refresh, size: 18),
             onPressed: () => setState(() {
@@ -224,21 +256,30 @@ class _BatchTrackingScreenState extends ConsumerState<BatchTrackingScreen> {
         (r.batchNo != null && r.batchNo!.isNotEmpty) ? r.batchNo! : null;
     switch (key) {
       case 'product':
-        return DataCell(Column(
-          crossAxisAlignment: CrossAxisAlignment.start,
-          mainAxisAlignment: MainAxisAlignment.center,
-          children: [
-            Text(r.productName ?? '-',
-                style: const TextStyle(
-                    fontSize: 13, fontWeight: FontWeight.w500)),
-            if (r.productCode != null)
-              Text(r.productCode!,
-                  style: const TextStyle(
-                      fontSize: 11,
-                      color: AppTheme.textSecondary,
-                      fontFamily: 'monospace')),
-          ],
-        ));
+        return DataCell(
+          GestureDetector(
+            onTap: () => context.push('/products/${r.productId}'),
+            child: Column(
+              crossAxisAlignment: CrossAxisAlignment.start,
+              mainAxisAlignment: MainAxisAlignment.center,
+              children: [
+                Text(r.productName ?? '-',
+                    style: const TextStyle(
+                        fontSize: 13,
+                        fontWeight: FontWeight.w500,
+                        color: AppTheme.primary,
+                        decoration: TextDecoration.underline,
+                        decorationColor: AppTheme.primary)),
+                if (r.productCode != null)
+                  Text(r.productCode!,
+                      style: const TextStyle(
+                          fontSize: 11,
+                          color: AppTheme.textSecondary,
+                          fontFamily: 'monospace')),
+              ],
+            ),
+          ),
+        );
       case 'spec':
         return DataCell(Text(r.productSpec ?? '-',
             style: const TextStyle(fontSize: 12)));