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>

backend/schema/schema.sql

@@ -102,7 +102,9 @@ CREATE TABLE IF NOT EXISTS `products` (
   `brand`         VARCHAR(100)    DEFAULT NULL COMMENT '品牌',
   `purchase_price` DECIMAL(16,2)  DEFAULT NULL COMMENT '参考进价',
   `sale_price`    DECIMAL(16,2)   DEFAULT NULL COMMENT '参考售价',
+  `public_id`     CHAR(36)        NOT NULL DEFAULT '' COMMENT 'UUID，公开URL使用',
   `min_stock`     INT             DEFAULT 0 COMMENT '库存预警值',
+  `description`   TEXT            DEFAULT NULL COMMENT '商品描述',
   `custom_fields` JSON            DEFAULT NULL COMMENT '动态扩展字段',
   `remark`        VARCHAR(500)    DEFAULT NULL,
   `created_at`    DATETIME        NOT NULL DEFAULT CURRENT_TIMESTAMP,
@@ -113,9 +115,25 @@ CREATE TABLE IF NOT EXISTS `products` (
   KEY `idx_category` (`category_id`),
   KEY `idx_deleted_at` (`deleted_at`),
   UNIQUE KEY `uk_product_code` (`shop_id`, `code`),
+  UNIQUE KEY `uk_public_id` (`public_id`),
   FULLTEXT KEY `ft_name` (`name`)
 ) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COMMENT='商品';
 
+-- ------------------------------------------------------------
+-- 商品图片
+-- ------------------------------------------------------------
+CREATE TABLE IF NOT EXISTS `product_images` (
+  `id`         BIGINT UNSIGNED NOT NULL AUTO_INCREMENT,
+  `product_id` BIGINT UNSIGNED NOT NULL,
+  `shop_id`    BIGINT UNSIGNED NOT NULL,
+  `url`        VARCHAR(500)    NOT NULL COMMENT '相对路径，如 /images/products/1/xxx.jpg',
+  `sort_order` INT             NOT NULL DEFAULT 0,
+  `created_at` DATETIME        NOT NULL DEFAULT CURRENT_TIMESTAMP,
+  PRIMARY KEY (`id`),
+  KEY `idx_product_id` (`product_id`),
+  KEY `idx_shop_id` (`shop_id`)
+) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COMMENT='商品图片';
+
 -- ------------------------------------------------------------
 -- 仓库
 -- ------------------------------------------------------------
@@ -146,6 +164,7 @@ CREATE TABLE IF NOT EXISTS `partners` (
   `phone`        VARCHAR(30)     DEFAULT NULL,
   `address`      VARCHAR(255)    DEFAULT NULL,
   `bank_account` VARCHAR(100)    DEFAULT NULL COMMENT '银行账号',
+  `status`       ENUM('enabled','disabled') NOT NULL DEFAULT 'enabled' COMMENT '正常/禁用',
   `custom_fields` JSON           DEFAULT NULL,
   `remark`       VARCHAR(500)    DEFAULT NULL,
   `created_at`   DATETIME        NOT NULL DEFAULT CURRENT_TIMESTAMP,
@@ -255,7 +274,7 @@ CREATE TABLE IF NOT EXISTS `stock_out_items` (
 -- ------------------------------------------------------------
 -- 库存（实时）
 -- ------------------------------------------------------------
-CREATE TABLE IF NOT EXISTS `inventory` (
+CREATE TABLE IF NOT EXISTS `inventories` (
   `id`           BIGINT UNSIGNED NOT NULL AUTO_INCREMENT,
   `shop_id`      BIGINT UNSIGNED NOT NULL,
   `warehouse_id` BIGINT UNSIGNED NOT NULL,
@@ -358,4 +377,50 @@ CREATE TABLE IF NOT EXISTS `number_rules` (
   UNIQUE KEY `uk_shop_type` (`shop_id`, `type`)
 ) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COMMENT='单号规则';
 
+-- ------------------------------------------------------------
+-- 基础数据选项
+-- ------------------------------------------------------------
+CREATE TABLE IF NOT EXISTS `product_name_options` (
+  `id`         BIGINT UNSIGNED NOT NULL AUTO_INCREMENT,
+  `shop_id`    BIGINT UNSIGNED NOT NULL,
+  `code`       VARCHAR(50)  DEFAULT NULL COMMENT '选项编号',
+  `name`       VARCHAR(200) NOT NULL    COMMENT '名称',
+  `remark`     VARCHAR(500) DEFAULT NULL,
+  `created_at` DATETIME NOT NULL DEFAULT CURRENT_TIMESTAMP,
+  `updated_at` DATETIME NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP,
+  `deleted_at` DATETIME DEFAULT NULL,
+  PRIMARY KEY (`id`),
+  KEY `idx_shop_id` (`shop_id`),
+  KEY `idx_deleted_at` (`deleted_at`)
+) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COMMENT='商品名称选项';
+
+CREATE TABLE IF NOT EXISTS `product_series_options` (
+  `id`         BIGINT UNSIGNED NOT NULL AUTO_INCREMENT,
+  `shop_id`    BIGINT UNSIGNED NOT NULL,
+  `code`       VARCHAR(50)  DEFAULT NULL COMMENT '选项编号',
+  `name`       VARCHAR(200) NOT NULL    COMMENT '系列名称',
+  `remark`     VARCHAR(500) DEFAULT NULL,
+  `created_at` DATETIME NOT NULL DEFAULT CURRENT_TIMESTAMP,
+  `updated_at` DATETIME NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP,
+  `deleted_at` DATETIME DEFAULT NULL,
+  PRIMARY KEY (`id`),
+  KEY `idx_shop_id` (`shop_id`),
+  KEY `idx_deleted_at` (`deleted_at`)
+) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COMMENT='商品系列选项';
+
+CREATE TABLE IF NOT EXISTS `product_spec_options` (
+  `id`         BIGINT UNSIGNED NOT NULL AUTO_INCREMENT,
+  `shop_id`    BIGINT UNSIGNED NOT NULL,
+  `code`       VARCHAR(50)  DEFAULT NULL COMMENT '选项编号',
+  `name`       VARCHAR(200) NOT NULL    COMMENT '规格名称',
+  `quantity`   INT          DEFAULT 0   COMMENT '单品数量',
+  `remark`     VARCHAR(500) DEFAULT NULL,
+  `created_at` DATETIME NOT NULL DEFAULT CURRENT_TIMESTAMP,
+  `updated_at` DATETIME NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP,
+  `deleted_at` DATETIME DEFAULT NULL,
+  PRIMARY KEY (`id`),
+  KEY `idx_shop_id` (`shop_id`),
+  KEY `idx_deleted_at` (`deleted_at`)
+) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COMMENT='商品规格选项';
+
 SET FOREIGN_KEY_CHECKS = 1;