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/router/index.js

@@ -0,0 +1,56 @@
+import { createRouter, createWebHistory } from 'vue-router'
+
+const routes = [
+  {
+    path: '/',
+    name: 'RecipeSearch',
+    component: () => import('../views/RecipeSearch.vue'),
+  },
+  {
+    path: '/manage',
+    name: 'RecipeManager',
+    component: () => import('../views/RecipeManager.vue'),
+  },
+  {
+    path: '/inventory',
+    name: 'Inventory',
+    component: () => import('../views/Inventory.vue'),
+  },
+  {
+    path: '/oils',
+    name: 'OilReference',
+    component: () => import('../views/OilReference.vue'),
+  },
+  {
+    path: '/projects',
+    name: 'Projects',
+    component: () => import('../views/Projects.vue'),
+  },
+  {
+    path: '/mydiary',
+    name: 'MyDiary',
+    component: () => import('../views/MyDiary.vue'),
+  },
+  {
+    path: '/audit',
+    name: 'AuditLog',
+    component: () => import('../views/AuditLog.vue'),
+  },
+  {
+    path: '/bugs',
+    name: 'BugTracker',
+    component: () => import('../views/BugTracker.vue'),
+  },
+  {
+    path: '/users',
+    name: 'UserManagement',
+    component: () => import('../views/UserManagement.vue'),
+  },
+]
+
+const router = createRouter({
+  history: createWebHistory(),
+  routes,
+})
+
+export default router