fix: 防止编辑配方意外清空成分 + 编辑器不直接引用store

- editRecipe不再直接引用store中的recipe对象（避免副作用）
- 保存时如果成分为空，弹出确认提示防止误操作
- 标签筛选时自动展开配方列表

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

frontend/src/views/RecipeManager.vue

@@ -744,7 +744,7 @@ function calcDilutionFromIngs() {
 }
 
 function editRecipe(recipe) {
-  editingRecipe.value = recipe
+  editingRecipe.value = { _id: recipe._id, _version: recipe._version, name: recipe.name }
   formName.value = recipe.name
   const ings = recipe.ingredients || []
   formIngredients.value = ings.filter(i => i.oil !== '椰子油').map(i => ({ ...i, _search: i.oil, _open: false }))
@@ -1016,12 +1016,17 @@ async function saveCurrentRecipe() {
   }
 
   if (editingRecipe.value && editingRecipe.value._id) {
-    // Editing an existing public recipe
+    // Editing an existing public recipe — safety check
+    const mappedIngs = cleanIngs.map(i => ({ oil_name: i.oil, drops: i.drops }))
+    if (mappedIngs.length === 0) {
+      const ok = await showConfirm('配方中没有精油成分，确定保存吗？这将清空所有成分。')
+      if (!ok) return
+    }
     const payload = {
       _id: editingRecipe.value._id,
       _version: editingRecipe.value._version,
       name: formName.value.trim(),
-      ingredients: cleanIngs.map(i => ({ oil_name: i.oil, drops: i.drops })),
+      ingredients: mappedIngs,
       note: formNote.value,
       tags: formTags.value,
     }