feat(shop): 门店 logo 上传 + 侧边栏品牌替换

- shops 表新增 logo_url 字段，AutoMigrate 自动建列
- 后端新增 POST /api/v1/shop/logo 接口（管理员），图片裁剪为 256×256 JPEG 存储
- UpdateInfo 支持传入 logo_url
- 侧边栏「岩美」替换为门店真实名称 + 自定义 logo
- 无 logo 时显示店名首字文字头像（深蓝底白字）
- 设置页「酒行信息」展示 logo 预览，编辑弹窗新增「更换 Logo」上传按钮
- 修复库存导入计数逻辑：total/imported/updated/errors 四项分别统计
- 库存导入去重改为双路索引（编号 + 名称|系列|规格），避免 key 不一致误判新增
- settings 页导入结果统一显示「重复 X 条」，兼容 skipped 和 updated 两个字段

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

backend/internal/handler/shop.go

@@ -1,11 +1,19 @@
 package handler
 
 import (
+	"fmt"
+	"image"
+	_ "image/jpeg"
+	_ "image/png"
 	"net/http"
+	"os"
+	"path/filepath"
 
+	"github.com/disintegration/imaging"
 	"github.com/gin-gonic/gin"
 	"gorm.io/gorm"
 
+	"github.com/wangjia/jiu/backend/config"
 	"github.com/wangjia/jiu/backend/internal/middleware"
 	"github.com/wangjia/jiu/backend/internal/model"
 )
@@ -38,6 +46,7 @@ func (h *ShopHandler) UpdateInfo(c *gin.Context) {
 		Address     string `json:"address"`
 		Phone       string `json:"phone"`
 		ManagerName string `json:"manager_name"`
+		LogoURL     string `json:"logo_url"`
 	}
 	if err := c.ShouldBindJSON(&req); err != nil {
 		c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
@@ -50,6 +59,9 @@ func (h *ShopHandler) UpdateInfo(c *gin.Context) {
 		"phone":        req.Phone,
 		"manager_name": req.ManagerName,
 	}
+	if req.LogoURL != "" {
+		updates["logo_url"] = req.LogoURL
+	}
 	if err := h.db.Model(&model.Shop{}).Where("id = ?", shopID).Updates(updates).Error; err != nil {
 		c.JSON(http.StatusInternalServerError, gin.H{"error": err.Error()})
 		return
@@ -59,3 +71,48 @@ func (h *ShopHandler) UpdateInfo(c *gin.Context) {
 	h.db.First(&shop, shopID)
 	c.JSON(http.StatusOK, shop)
 }
+
+// UploadLogo POST /api/v1/shop/logo  (admin only)
+func (h *ShopHandler) UploadLogo(c *gin.Context) {
+	shopID := middleware.GetShopID(c)
+
+	if err := c.Request.ParseMultipartForm(2 << 20); err != nil {
+		c.JSON(http.StatusBadRequest, gin.H{"error": "文件超过 2MB 限制"})
+		return
+	}
+	file, _, err := c.Request.FormFile("file")
+	if err != nil {
+		c.JSON(http.StatusBadRequest, gin.H{"error": "请上传文件（field: file）"})
+		return
+	}
+	defer file.Close()
+
+	img, _, err := image.Decode(file)
+	if err != nil {
+		c.JSON(http.StatusBadRequest, gin.H{"error": "仅支持 JPEG/PNG 图片"})
+		return
+	}
+
+	// 裁剪为正方形后缩放到 256×256
+	resized := imaging.Fill(img, 256, 256, imaging.Center, imaging.Lanczos)
+
+	subdir := filepath.Join(config.C.Storage.UploadDir, "shops", fmt.Sprintf("%d", shopID))
+	if err := os.MkdirAll(subdir, 0755); err != nil {
+		c.JSON(http.StatusInternalServerError, gin.H{"error": "存储目录创建失败"})
+		return
+	}
+	fullPath := filepath.Join(subdir, "logo.jpg")
+
+	if err := imaging.Save(resized, fullPath, imaging.JPEGQuality(90)); err != nil {
+		c.JSON(http.StatusInternalServerError, gin.H{"error": "图片保存失败"})
+		return
+	}
+
+	logoURL := fmt.Sprintf("/images/shops/%d/logo.jpg", shopID)
+	if err := h.db.Model(&model.Shop{}).Where("id = ?", shopID).Update("logo_url", logoURL).Error; err != nil {
+		c.JSON(http.StatusInternalServerError, gin.H{"error": err.Error()})
+		return
+	}
+
+	c.JSON(http.StatusOK, gin.H{"logo_url": logoURL})
+}