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>

backend/internal/handler/public.go

@@ -2,6 +2,8 @@ package handler
 
 import (
 	"net/http"
+	"os"
+	"time"
 
 	"github.com/gin-gonic/gin"
 	"gorm.io/gorm"
@@ -29,7 +31,37 @@ func (h *PublicHandler) GetProduct(c *gin.Context) {
 		return
 	}
 
-	// Return only public-safe fields (no price/stock info)
+	// Fetch shop public info
+	var shop model.Shop
+	shopData := gin.H{}
+	if err := h.db.Where("id = ?", product.ShopID).First(&shop).Error; err == nil {
+		shopData = gin.H{
+			"name":           shop.Name,
+			"code":           shop.Code,
+			"address":        shop.Address,
+			"phone":          shop.Phone,
+			"business_hours": shop.BusinessHours,
+		}
+	}
+
+	// Fetch latest inventory batch for this product
+	var inv model.Inventory
+	batchData := gin.H(nil)
+	if err := h.db.Where("product_id = ? AND quantity > 0 AND deleted_at IS NULL", product.ID).
+		Order("created_at DESC").
+		First(&inv).Error; err == nil {
+		var pdStr *string
+		if inv.ProductionDate != nil {
+			s := inv.ProductionDate.Time.Format("2006-01-02")
+			pdStr = &s
+		}
+		batchData = gin.H{
+			"production_date": pdStr,
+			"batch_no":        inv.BatchNo,
+			"in_stock_date":   inv.CreatedAt.Format("2006-01-02"),
+		}
+	}
+
 	c.JSON(http.StatusOK, gin.H{
 		"data": gin.H{
 			"id":          product.ID,
@@ -40,6 +72,31 @@ func (h *PublicHandler) GetProduct(c *gin.Context) {
 			"unit":        product.Unit,
 			"description": product.Description,
 			"images":      product.Images,
+			"shop":        shopData,
+			"batch":       batchData,
 		},
 	})
 }
+
+// GetRelease GET /api/v1/public/release (no auth)
+func (h *PublicHandler) GetRelease(c *gin.Context) {
+	version := os.Getenv("APP_VERSION")
+	if version == "" {
+		version = "1.0.0"
+	}
+	buildDate := os.Getenv("BUILD_DATE")
+	if buildDate == "" {
+		buildDate = time.Now().Format("2006-01-02")
+	}
+
+	c.JSON(http.StatusOK, gin.H{
+		"version":    version,
+		"build_date": buildDate,
+		"download_urls": gin.H{
+			"macos":   os.Getenv("DOWNLOAD_URL_MACOS"),
+			"windows": os.Getenv("DOWNLOAD_URL_WINDOWS"),
+			"web":     "https://jiu.51yanmei.com/app",
+		},
+		"changelog": []gin.H{},
+	})
+}