feat: 未登录用户也显示二维码上传提示，点击时引导登录/注册

frontend/src/components/RecipeDetailOverlay.vue

@@ -466,12 +466,16 @@ async function loadBrand() {
   }
 }
 
-// Whether to show the brand/QR upload hint
+// Whether to show the brand/QR upload hint (show to all users who haven't set up brand assets)
 const showBrandHint = computed(() =>
-  authStore.isLoggedIn && !!brand.value && !brand.value.qr_code && !brand.value.brand_bg
+  !!brand.value && !brand.value.qr_code && !brand.value.brand_bg
 )
 
 function goUploadQr() {
+  if (!authStore.isLoggedIn) {
+    ui.openLogin()
+    return
+  }
   if (recipe.value._id) {
     localStorage.setItem('oil_return_recipe_id', recipe.value._id)
   }