feat: 配方卡片加入上传个人二维码功能

- RecipeDetailOverlay: 未上传二维码/背景图时，卡片上方显示提示横幅，下方出现「上传我的二维码」按钮，点击跳转到 MyDiary 品牌设置页并记录来源配方
- MyDiary: 新增二维码图片上传区域（直接上传图片文件，存为 base64 → PUT /api/brand qr_code 字段）；上传成功后若有待返回配方则自动跳回配方卡片；修复 loadBrandSettings 字段名与后端不一致的问题
- RecipeSearch: 支持 ?openRecipe= 查询参数，页面挂载时自动打开指定配方卡片，实现从 MyDiary 上传后无缝返回

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

frontend/src/views/RecipeSearch.vue

@@ -123,7 +123,8 @@
 </template>
 
 <script setup>
-import { ref, computed, onMounted, nextTick } from 'vue'
+import { ref, computed, onMounted, nextTick, watch } from 'vue'
+import { useRoute, useRouter } from 'vue-router'
 import { useAuthStore } from '../stores/auth'
 import { useOilsStore } from '../stores/oils'
 import { useRecipesStore } from '../stores/recipes'
@@ -136,6 +137,8 @@ const auth = useAuthStore()
 const oils = useOilsStore()
 const recipeStore = useRecipesStore()
 const ui = useUiStore()
+const route = useRoute()
+const router = useRouter()
 
 const searchQuery = ref('')
 const selectedCategory = ref(null)
@@ -154,6 +157,27 @@ onMounted(async () => {
   } catch {
     // category modules are optional
   }
+
+  // Return to a recipe card after QR upload redirect
+  const openRecipeId = route.query.openRecipe
+  if (openRecipeId) {
+    router.replace({ path: '/', query: {} })
+    const tryOpen = () => {
+      const idx = recipeStore.recipes.findIndex(r => r._id === openRecipeId)
+      if (idx >= 0) {
+        openDetail(idx)
+        return true
+      }
+      return false
+    }
+    if (!tryOpen()) {
+      // Recipes might not be loaded yet, watch until available
+      const stop = watch(
+        () => recipeStore.recipes.length,
+        () => { if (tryOpen()) stop() },
+      )
+    }
+  }
 })
 
 function selectCategory(cat) {