Refactor frontend to Vue 3 + Vite + Pinia + Cypress E2E

- Replace single-file 8441-line HTML with Vue 3 SPA
- Pinia stores: auth, oils, recipes, diary, ui
- Composables: useApi, useDialog, useSmartPaste, useOilTranslation
- 6 shared components: RecipeCard, RecipeDetailOverlay, TagPicker, etc.
- 9 page views: RecipeSearch, RecipeManager, Inventory, OilReference, etc.
- 14 Cypress E2E test specs (113 tests), all passing
- Multi-stage Dockerfile (Node build + Python runtime)
- Demo video generation scripts (TTS + subtitles + screen recording)

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

frontend/scripts/demo-subtitles.srt

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+欢迎使用 doTERRA 精油配方计算器，这是一个功能完整的精油配方管理工具
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+00:00:05,000 --> 00:00:08,500
+首页展示了所有公共配方，以卡片形式排列
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+00:00:09,000 --> 00:00:11,500
+可以上下滚动浏览更多配方
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+00:00:12,000 --> 00:00:15,500
+在搜索框输入关键词，可以快速筛选配方
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+00:00:16,000 --> 00:00:19,500
+输入"薰衣草"，立即过滤出包含薰衣草的配方
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+00:00:20,000 --> 00:00:24,000
+点击任意配方卡片，查看配方详情
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+00:00:24,500 --> 00:00:29,000
+详情页显示精油成分、用量、单价和总成本
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+00:00:30,000 --> 00:00:34,000
+切换到"精油价目"页面，查看所有精油价格
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+00:00:34,500 --> 00:00:37,500
+支持按名称搜索精油
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+00:00:38,000 --> 00:00:41,500
+可以切换"瓶价"和"滴价"两种显示模式
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+00:00:42,000 --> 00:00:46,500
+"管理配方"页面用于配方的增删改查和批量操作
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+00:00:47,000 --> 00:00:51,000
+支持标签筛选、批量打标签、批量导出卡片
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+00:00:52,000 --> 00:00:56,000
+"个人库存"页面标记自己拥有的精油
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+00:00:56,500 --> 00:00:59,500
+系统会自动推荐你能制作的配方
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+00:01:00,000 --> 00:01:05,000
+"操作日志"记录所有数据变更，支持按类型和用户筛选
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+00:01:06,000 --> 00:01:10,500
+内置 Bug 追踪系统，支持优先级、状态流转和评论
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+"用户管理"可以创建用户、分配角色、审核翻译建议
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+最后回到首页，演示到此结束
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+00:01:22,500 --> 00:01:26,000
+感谢观看！这是基于 Vue 3 + Vite + Pinia 构建的现代化应用