Deploy OpenCite to GitHub Pages

[beanbean9339]

Set up GitHub Pages deployment so OpenCite is publicly accessible as a static site.

Tasks

• Configure GitHub Pages in repository settings
• Ensure Vite production build works correctly with Pages
• Verify routing works in production
• Confirm all assets load correctly

Acceptance criteria

• App is accessible via GitHub Pages URL
• npm run build produces a working production bundle
• No broken paths or missing assets in deployed version