fix: 批量改标签只发送tags字段，不发送整个recipe

修复因ingredients格式不匹配(oil vs oil_name)导致PUT请求失败
标签修改实际未保存到数据库的问题

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

frontend/src/views/RecipeManager.vue

@@ -601,15 +601,22 @@ async function applyBatchTags() {
   for (const id of pubIds) {
     const recipe = recipeStore.recipes.find(r => r._id === id)
     if (!recipe) continue
+    let newTags = [...recipe.tags]
     let changed = false
     for (const t of tagsToAdd) {
-      if (!recipe.tags.includes(t)) { recipe.tags.push(t); changed = true }
+      if (!newTags.includes(t)) { newTags.push(t); changed = true }
     }
     for (const t of tagsToRemove) {
-      const idx = recipe.tags.indexOf(t)
+      const idx = newTags.indexOf(t)
-      if (idx >= 0) { recipe.tags.splice(idx, 1); changed = true }
+      if (idx >= 0) { newTags.splice(idx, 1); changed = true }
+    }
+    if (changed) {
+      await api(`/api/recipes/${recipe._id}`, {
+        method: 'PUT',
+        body: JSON.stringify({ tags: newTags }),
+      })
+      recipe.tags = newTags
     }
-    if (changed) await recipeStore.saveRecipe(recipe)
   }
   for (const id of diaryIds) {
     const d = diaryStore.userDiary.find(r => r.id === id)