feat: 新增产品表单(ml/g/颗)+配方卡片显示产品容量

- 精油价目新增分两个tab：新增精油(标准容量) / 新增其他产品(ml/g/颗)
- saveOil支持unit参数
- 配方卡片：含产品的配方直接显示产品用量+单位(如30g)

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

frontend/src/stores/oils.js

@@ -77,14 +77,16 @@ export const useOilsStore = defineStore('oils', () => {
     oilsMeta.value = newMeta
   }
 
-  async function saveOil(name, bottlePrice, dropCount, retailPrice, enName = null) {
-    await api.post('/api/oils', {
+  async function saveOil(name, bottlePrice, dropCount, retailPrice, enName = null, unit = null) {
+    const payload = {
       name,
       bottle_price: bottlePrice,
       drop_count: dropCount,
       retail_price: retailPrice,
       en_name: enName,
-    })
+    }
+    if (unit) payload.unit = unit
+    await api.post('/api/oils', payload)
     await loadOils()
   }