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/cypress/e2e/api-health.cy.js

@@ -0,0 +1,64 @@
+describe('API Health Check', () => {
+  it('GET /api/version returns version', () => {
+    cy.request('/api/version').then(res => {
+      expect(res.status).to.eq(200)
+      expect(res.body).to.have.property('version')
+    })
+  })
+
+  it('GET /api/oils returns oil list', () => {
+    cy.request('/api/oils').then(res => {
+      expect(res.status).to.eq(200)
+      expect(res.body).to.be.an('array')
+      expect(res.body.length).to.be.gte(1)
+      const oil = res.body[0]
+      expect(oil).to.have.property('name')
+      expect(oil).to.have.property('bottle_price')
+      expect(oil).to.have.property('drop_count')
+    })
+  })
+
+  it('GET /api/recipes returns recipe list', () => {
+    cy.request('/api/recipes').then(res => {
+      expect(res.status).to.eq(200)
+      expect(res.body).to.be.an('array')
+      if (res.body.length > 0) {
+        const recipe = res.body[0]
+        expect(recipe).to.have.property('name')
+        expect(recipe).to.have.property('ingredients')
+      }
+    })
+  })
+
+  it('GET /api/tags returns tags array', () => {
+    cy.request('/api/tags').then(res => {
+      expect(res.status).to.eq(200)
+      expect(res.body).to.be.an('array')
+    })
+  })
+
+  it('GET /api/me returns anonymous user without auth', () => {
+    cy.request('/api/me').then(res => {
+      expect(res.status).to.eq(200)
+      expect(res.body.username).to.eq('anonymous')
+      expect(res.body.role).to.eq('viewer')
+    })
+  })
+
+  it('GET /api/me returns authenticated user with valid token', () => {
+    // Use the admin token from env or skip
+    const token = Cypress.env('ADMIN_TOKEN')
+    if (!token) {
+      cy.log('ADMIN_TOKEN not set, skipping auth test')
+      return
+    }
+    cy.request({
+      url: '/api/me',
+      headers: { Authorization: `Bearer ${token}` }
+    }).then(res => {
+      expect(res.status).to.eq(200)
+      expect(res.body.id).to.not.be.null
+      expect(res.body.username).to.not.eq('anonymous')
+    })
+  })
+})