fix(backend): 商品公开页移除「在 App 中查看」链接

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01JJ1g8XV1YhhmHRzhwWEW7o

backend/internal/handler/public_page.go

@@ -192,7 +192,6 @@ type productPageVM struct {
 	ShopAddr  string
 	ShopHours string
 	ShopWx    string
-	AppURL    string
 }
 
 // ProductPage GET /product/:public_id
@@ -235,7 +234,6 @@ func (h *PublicHandler) ProductPage(c *gin.Context) {
 		Origin:    d.Origin,
 		ShelfLife: d.ShelfLife,
 		Storage:   d.Storage,
-		AppURL:    "/app/product/" + p.PublicID,
 	}
 	for _, img := range p.Images {
 		if img.URL != "" {