[Frontend][Tech-debt] Demo page shipped as a production route (/demo)

[Penielka]

Overview

frontend/src/app/demo/page.tsx is a "Profile Management Dashboard" demo page mounted as the public /demo route. It is demo/marketing scaffolding (mock data, alert() on save, "Choose a Demo" UI) that ships in production builds and is discoverable by users.

Evidence

• frontend/src/app/demo/page.tsx

Acceptance Criteria

• Remove the route or move it behind a feature flag / non-production guard
• Add a test that the demo route 404s in production builds

Files to Modify

• frontend/src/app/demo/page.tsx

Priority: Low