Merge three pages into single SPA

[zhangzhenghao]

Summary

Consolidate login, privacy, and index pages into one Vue Single Page Application.

Changes

Frontend

• Use Vue Router for client-side routing with history mode (clean URLs without hash)
• Create MainLayout component for shared navigation bar
• Move Login and Privacy pages to Vue Router components
• Single entry point: index.html

Backend (Flask)

• Update routes to serve single index.html for all frontend routes
• Add /logout route for user logout
• Catch-all route for SPA history mode support

File Structure

• src/main.js - unified entry point
• src/App.vue - root component with router-view
• src/layouts/MainLayout.vue - shared navigation layout
• src/views/ - Home, Favorites, Login, Privacy
• src/components/Preloader.vue - shared component

Benefits

• Simpler project structure
• Clean URLs (history mode)
• Better code organization
• Shared navigation and layout

Test Plan

1. pnpm build - successful build
2. Run Flask server
3. Navigate between pages using Vue Router
4. Test logout functionality