fix: Logo放在总成本下方靠左，QR与标题顶端/日期右侧对齐

- Logo: 从absolute改为flow layout，放在总成本和制作日期之间
  左侧显示logo，右侧显示制作日期（flex space-between）
  没有logo时日期仍靠右
- QR: right改为36px（与卡片padding对齐），top微调到34px
  右边缘与制作日期右侧对齐

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

frontend/src/components/RecipeDetailOverlay.vue

@@ -63,13 +63,6 @@
             />
             <div v-if="brand.brand_name" class="card-qr-name">{{ brand.brand_name }}</div>
           </div>
-          <img
-            v-if="brand.brand_logo"
-            :src="brand.brand_logo"
-            class="card-logo"
-            crossorigin="anonymous"
-          />
-
           <div class="card-content">
             <div class="card-brand-text">
               {{ cardLang === 'en' ? 'doTERRA · Gifts of the Earth' : 'doTERRA · 来自大地的礼物' }}
@@ -117,9 +110,18 @@
               </div>
             </div>
 
-            <!-- Date -->
-            <div class="card-footer">
-              {{ cardLang === 'en' ? 'Date: ' : '制作日期：' }}{{ todayStr }}
+            <!-- Logo + Date row -->
+            <div class="card-bottom-row">
+              <img
+                v-if="brand.brand_logo"
+                :src="brand.brand_logo"
+                class="card-logo"
+                crossorigin="anonymous"
+              />
+              <div v-else class="card-logo-placeholder"></div>
+              <div class="card-footer">
+                {{ cardLang === 'en' ? 'Date: ' : '制作日期：' }}{{ todayStr }}
+              </div>
             </div>
           </div>
         </div>
@@ -1141,8 +1143,8 @@ async function saveRecipe() {
 
 .card-qr-wrapper {
   position: absolute;
-  top: 36px;
-  right: 24px;
+  top: 34px;
+  right: 36px;
   display: flex;
   flex-direction: column;
   align-items: center;
@@ -1168,14 +1170,18 @@ async function saveRecipe() {
 }
 
 .card-logo {
-  position: absolute;
-  bottom: 60px;
-  left: 24px;
-  height: 60px;
+  height: 28px;
   object-fit: contain;
-  z-index: 1;
-  opacity: 0.2;
-  pointer-events: none;
+  opacity: 0.6;
+}
+.card-logo-placeholder {
+  /* keeps footer right-aligned even without logo */
+}
+.card-bottom-row {
+  display: flex;
+  justify-content: space-between;
+  align-items: flex-end;
+  margin-top: 16px;
 }
 
 .card-brand-text {
@@ -1298,7 +1304,6 @@ async function saveRecipe() {
 }
 
 .card-footer {
-  margin-top: 16px;
   text-align: right;
   font-size: 11px;
   color: var(--text-light, #9a8570);