fix: 植物空胶囊全局显示"颗"(capsule)，配方卡片/编辑器/价目统一

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

frontend/src/stores/oils.js

@@ -105,11 +105,13 @@ export const useOilsStore = defineStore('oils', () => {
 
   function unitLabel(name, lang = 'zh') {
     if (isMlUnit(name)) return 'ml'
+    if (name === '植物空胶囊') return lang === 'en' ? 'capsule' : '颗'
     return lang === 'en' ? 'drop' : '滴'
   }
 
   function unitLabelPlural(name, count, lang = 'zh') {
     if (isMlUnit(name)) return 'ml'
+    if (name === '植物空胶囊') return lang === 'en' ? (count === 1 ? 'capsule' : 'capsules') : '颗'
     return lang === 'en' ? (count === 1 ? 'drop' : 'drops') : '滴'
   }