fix: 精油编辑统一保存到 DB + 导出 Excel 增加功效列

- 新增 oil_cards 表，持久化知识卡片（功效/用法/方法/注意/emoji）
- POST /api/oils 扩展接受 card_* 字段，在同一事务里 upsert oil_cards
- GET /api/oil-cards 返回全部卡片
- 前端 getOilCard 优先查 DB，再 fallback 静态表
- saveEditOil 统一走 saveOil，不再分两套保存
- 精油价目 Excel 导出增加「功效」列
- 首次部署自动从静态 OIL_CARDS 播种到 oil_cards 表

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

frontend/src/stores/oils.js

@@ -16,6 +16,7 @@ export const VOLUME_DROPS = {
 export const useOilsStore = defineStore('oils', () => {
   const oils = ref({})
   const oilsMeta = ref({})
+  const oilCards = ref({})
 
   // Getters
   const oilNames = computed(() =>
@@ -79,9 +80,28 @@ export const useOilsStore = defineStore('oils', () => {
     }
     oils.value = newOils
     oilsMeta.value = newMeta
+
+    // Also fetch oil cards from DB
+    try {
+      const cards = await api.get('/api/oil-cards')
+      const newCards = {}
+      for (const card of cards) {
+        newCards[card.name] = {
+          emoji: card.emoji || '',
+          en: card.en || '',
+          effects: card.effects || '',
+          usage: card.usage || '',
+          method: card.method || '',
+          caution: card.caution || '',
+        }
+      }
+      oilCards.value = newCards
+    } catch {
+      // oil_cards table may not exist yet on older backends
+    }
   }
 
-  async function saveOil(name, bottlePrice, dropCount, retailPrice, enName = null, unit = null) {
+  async function saveOil(name, bottlePrice, dropCount, retailPrice, enName = null, unit = null, card = null) {
     const payload = {
       name,
       bottle_price: bottlePrice,
@@ -90,6 +110,13 @@ export const useOilsStore = defineStore('oils', () => {
       en_name: enName,
     }
     if (unit) payload.unit = unit
+    if (card) {
+      payload.card_emoji = card.emoji ?? null
+      payload.card_effects = card.effects ?? null
+      payload.card_usage = card.usage ?? null
+      payload.card_method = card.method ?? null
+      payload.card_caution = card.caution ?? null
+    }
     await api.post('/api/oils', payload)
     await loadOils()
   }
@@ -138,6 +165,7 @@ export const useOilsStore = defineStore('oils', () => {
   return {
     oils,
     oilsMeta,
+    oilCards,
     oilNames,
     pricePerDrop,
     calcCost,