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/src/stores/diary.js

@@ -0,0 +1,56 @@
+import { defineStore } from 'pinia'
+import { ref } from 'vue'
+import { api } from '../composables/useApi'
+
+export const useDiaryStore = defineStore('diary', () => {
+  const userDiary = ref([])
+  const currentDiaryId = ref(null)
+
+  // Actions
+  async function loadDiary() {
+    const data = await api.get('/api/diary')
+    userDiary.value = data
+  }
+
+  async function createDiary(data) {
+    const result = await api.post('/api/diary', data)
+    await loadDiary()
+    return result
+  }
+
+  async function updateDiary(id, data) {
+    const result = await api.put(`/api/diary/${id}`, data)
+    await loadDiary()
+    return result
+  }
+
+  async function deleteDiary(id) {
+    await api.delete(`/api/diary/${id}`)
+    userDiary.value = userDiary.value.filter((d) => (d._id ?? d.id) !== id)
+    if (currentDiaryId.value === id) {
+      currentDiaryId.value = null
+    }
+  }
+
+  async function addEntry(diaryId, content) {
+    const result = await api.post(`/api/diary/${diaryId}/entries`, content)
+    await loadDiary()
+    return result
+  }
+
+  async function deleteEntry(entryId) {
+    await api.delete(`/api/diary/entries/${entryId}`)
+    await loadDiary()
+  }
+
+  return {
+    userDiary,
+    currentDiaryId,
+    loadDiary,
+    createDiary,
+    updateDiary,
+    deleteDiary,
+    addEntry,
+    deleteEntry,
+  }
+})