Add automated deployment workflow for the static site

[haljac]

Problem

There is no automated deployment. After CI passes on main, someone must manually deploy the built static site. This slows down iteration and introduces risk of deploying stale builds.

Scope of Work

Create .github/workflows/deploy.yml:

• Trigger: on push to main, only after CI workflow succeeds (use workflow_run or make it a job in the existing workflow)
• Build: run npm run build to produce dist/
• Deploy: push dist/ to the hosting provider

Hosting decision needed

The deployment target needs to be decided before implementation:

• GitHub Pages — simplest setup, use actions/deploy-pages. Free for public repos.
• GCP (Cloud Run / Cloud Storage) — more control, needs OIDC auth setup with google-github-actions/auth.
• Other (Netlify, Vercel, Cloudflare Pages) — evaluate if preferred.

Environment protection

• Use GitHub Environments with required reviewers for production (optional for initial setup)
• Store deployment credentials as repository secrets

Acceptance Criteria

• Deployment target is decided and documented
• .github/workflows/deploy.yml exists and deploys on push to main
• Deployment only runs after CI checks pass
• Site is accessible at the production URL after a successful deploy
• Deployment credentials are stored as secrets (not in code)
• Failed deploys don't leave the site in a broken state (atomic deploy or rollback)