feat(backend): 二维码链接统一改为 /app/product/ 路径，消除 URL 跳变

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

CHANGELOG.md

@@ -5,6 +5,11 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
+## [1.0.49] - 2026-06-15
+
+### 改进
+- 二维码链接统一使用 `/app/product/` 路径，扫码后 URL 不再跳变，分享与打开同一个链接
+
 ## [1.0.48] - 2026-06-15
 
 ### 修复

backend/internal/handler/product.go

@@ -198,7 +198,7 @@ func (h *ProductHandler) QRCode(c *gin.Context) {
 		h.db.Model(&product).Update("public_id", product.PublicID)
 	}
 
-	url := config.C.Storage.PublicURL + "/product/" + product.PublicID
+	url := config.C.Storage.PublicURL + "/app/product/" + product.PublicID
 	if product.Code != "" {
 		url += "?code=" + product.Code
 	}

backend/internal/handler/public.go

@@ -369,7 +369,7 @@ func buildProductOG(product model.Product, shopName, publicURL string) string {
 	}
 
 	// og:url
-	pageURL := publicURL + "/product/" + product.PublicID
+	pageURL := publicURL + "/app/product/" + product.PublicID
 
 	var sb strings.Builder
 	sb.WriteString("\n")