fix: 容量和稀释比例无默认选择

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

frontend/src/views/RecipeManager.vue

@@ -438,7 +438,7 @@ const newIngOil = ref('')
 const newIngSearch = ref('')
 const newIngDrops = ref(1)
 const newIngDropdownOpen = ref(false)
-const formVolume = ref('30')
+const formVolume = ref('')
 const formCustomVolume = ref(null)
 const formCustomUnit = ref('drops')
 const formDilution = ref(6)
@@ -732,39 +732,8 @@ async function executeBatchAction(action) {
   clearSelection()
 }
 
-function calcDilutionFromIngs(ingredients) {
-  const ings = ingredients || []
-  const coco = ings.find(i => i.oil === '椰子油')
-  const eoDrops = ings.filter(i => i.oil && i.oil !== '椰子油').reduce((s, i) => s + (i.drops || 0), 0)
-  const cocoDrops = coco ? (coco.drops || 0) : 0
-  const totalDrops = eoDrops + cocoDrops
-
-  // Set dilution ratio
-  if (eoDrops > 0 && cocoDrops > 0) {
-    const ratio = Math.round(cocoDrops / eoDrops)
-    // Clamp to available options
-    const options = [3,4,5,6,7,8,9,10,12,15,20]
-    formDilution.value = options.reduce((prev, curr) => Math.abs(curr - ratio) < Math.abs(prev - ratio) ? curr : prev)
-  }
-
-  // Set coconut drops for single mode
-  if (coco) {
-    formCocoRow.value.drops = cocoDrops
-  }
-
-  // Guess volume
-  if (!coco || cocoDrops === 0) {
-    formVolume.value = 'single'
-  } else {
-    const ml = totalDrops / DROPS_PER_ML
-    if (ml <= 2) formVolume.value = 'single'
-    else if (Math.abs(ml - 5) < 1.5) formVolume.value = '5'
-    else if (Math.abs(ml - 10) < 2.5) formVolume.value = '10'
-    else if (Math.abs(ml - 15) < 2.5) formVolume.value = '15'
-    else if (Math.abs(ml - 20) < 3) formVolume.value = '20'
-    else if (Math.abs(ml - 30) < 6) formVolume.value = '30'
-    else { formVolume.value = 'custom'; formCustomVolume.value = Math.round(ml) }
-  }
+function calcDilutionFromIngs() {
+  // No default selection — user chooses
 }
 
 function editRecipe(recipe) {
@@ -798,7 +767,7 @@ function resetForm() {
   newIngOil.value = ''
   newIngSearch.value = ''
   newIngDrops.value = 1
-  formVolume.value = '30'
+  formVolume.value = ''
   formCustomVolume.value = null
   formDilution.value = 6
 }