frontend: production deploy pipeline for cauweb (Vercel/Netlify + Docker alternative)

[ayushkrtiwari]

Goal

Provide deploy options and instructions for cauweb: static hosting (Vercel/Netlify) and Dockerized serving.

Tasks

• Add vercel.json (or netlify.toml) with build commands and rewrites for /api.
• Add Dockerfile.frontend to build the app and serve via nginx.
• Add a GitHub Actions workflow that builds frontend, runs tests, and optionally deploys to staging.
• Document steps for DNS, environment vars, and SSL.

Acceptance criteria

• One-click deploy instructions for Vercel/Netlify documented and tested.
• Docker image builds and serves site locally.