Set up Continuous Deployment pipeline

## Objective

Create a CD pipeline to automate deployment to production after a successful CI run on the main branch.

## Context

Continuous Deployment ensures that every change merged to the main branch is automatically built and deployed, reducing manual overhead and accelerating delivery.

## Checklist

- [ ] Define deployment target (e.g. VPS, container registry, PaaS)
- [ ] Configure build step for production
- [ ] Set up deployment credentials as GitHub Secrets
- [ ] Create CD workflow (`.github/workflows/cd.yml`)
- [ ] Add health-check verification post-deployment
- [ ] Document rollback procedure

## Definition of Done

- Every push to `main` that passes CI is automatically deployed.
- Deployment completes in under 10 minutes.
- Rollback is possible within 2 minutes.

Start by determining the deployment target and reviewing the existing CI workflow for the TypeScript project. Create .github/workflows/cd.yml to deploy successful main-branch builds, add health-check verification and rollback documentation, and confirm deployments finish within 10 minutes with rollback possible within 2 minutes.

Written by the indexing model from the issue text.