fix: 配方卡片QR恢复absolute定位+padding-right避让，预览图修正

配方卡片:
- QR恢复absolute(top:36px right:36px)，不用float避免文字环绕
- card-content加padding-right:70px给QR留空间
- 文字不会被QR挤压

预览图:
- QR+品牌名放在右上角area里(absolute定位)
- 品牌名文字显示在QR图片下方
- 内容区padding-right:60px避让QR

返回配方:
- openRecipe参数用String比较修复类型不匹配

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

frontend/src/components/RecipeDetailOverlay.vue

@@ -55,12 +55,12 @@
             class="card-brand-bg"
             :style="{ backgroundImage: `url('${brand.brand_bg}')` }"
           />
+          <!-- QR: absolute positioned in export-card, top-right corner of content area -->
+          <div v-if="brand.qr_code" class="card-qr-wrapper">
+            <img :src="brand.qr_code" class="card-qr" crossorigin="anonymous" />
+            <div v-if="brand.brand_name" class="card-qr-name">{{ brand.brand_name }}</div>
+          </div>
           <div class="card-content">
-            <!-- QR floated right, aligns with brand text top -->
-            <div v-if="brand.qr_code" class="card-qr-float">
-              <img :src="brand.qr_code" class="card-qr" crossorigin="anonymous" />
-              <div v-if="brand.brand_name" class="card-qr-name">{{ brand.brand_name }}</div>
-            </div>
             <div class="card-brand-text">
               {{ cardLang === 'en' ? 'doTERRA · Gifts of the Earth' : 'doTERRA · 来自大地的礼物' }}
             </div>
@@ -1122,6 +1122,7 @@ async function saveRecipe() {
 .card-content {
   position: relative;
   z-index: 2;
+  padding-right: 70px; /* leave room for QR */
 }
 
 /* Brand overlays */
@@ -1138,14 +1139,15 @@ async function saveRecipe() {
   pointer-events: none;
 }
 
-.card-qr-float {
-  float: right;
+.card-qr-wrapper {
+  position: absolute;
+  top: 36px;
+  right: 36px;
   display: flex;
   flex-direction: column;
   align-items: center;
   gap: 3px;
-  margin-left: 12px;
-  margin-bottom: 8px;
+  z-index: 3;
 }
 
 .card-qr {