fix: HEIC上传修复 + 去掉保存按钮改为自动保存

- HEIC检测兼容MIME type和文件名
- heic2any返回数组时取第一个
- 转换失败时提示用户手动转JPG
- 去掉保存品牌按钮，显示"所有修改自动保存"

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

frontend/src/views/MyDiary.vue

@@ -199,7 +199,7 @@
         </div>
 
         <div style="display:flex;gap:8px;align-items:center">
-          <button class="btn btn-primary" @click="saveBrandSettings">💾 保存品牌设置</button>
+          <span class="auto-save-hint">所有修改自动保存</span>
           <button v-if="returnRecipeId" class="btn btn-outline" @click="goBackToRecipe">← 返回配方卡片</button>
         </div>
       </div>
@@ -577,11 +577,19 @@ async function handleUpload(type, event) {
   if (!file) return
   try {
     // Convert HEIC/HEIF to JPEG
-    if (file.name.toLowerCase().match(/\.hei[cf]$/)) {
+    const isHeic = file.name.toLowerCase().match(/\.hei[cf]$/) ||
+      file.type === 'image/heic' || file.type === 'image/heif'
+    if (isHeic) {
       ui.showToast('正在转换HEIC格式...')
+      try {
         const heic2any = (await import('heic2any')).default
-      const blob = await heic2any({ blob: file, toType: 'image/jpeg', quality: 0.8 })
-      file = new File([blob], file.name.replace(/\.hei[cf]$/i, '.jpg'), { type: 'image/jpeg' })
+        let blob = await heic2any({ blob: file, toType: 'image/jpeg', quality: 0.8 })
+        if (Array.isArray(blob)) blob = blob[0]
+        file = new File([blob], 'photo.jpg', { type: 'image/jpeg' })
+      } catch (e) {
+        ui.showToast('HEIC转换失败，请手动转为JPG后上传')
+        return
+      }
     }
     let base64 = await readFileAsBase64(file)
 
@@ -1158,6 +1166,8 @@ async function applyBusiness() {
   margin-bottom: 12px;
 }
 
+.auto-save-hint { font-size: 12px; color: #999; font-style: italic; }
+
 .verified-badge {
   padding: 12px;
   background: #e8f5e9;