ci: add Docker CI/CD pipeline and deployment automation

[victorbruce]

🎯 What This PR Does

Adds Docker CI/CD pipeline with automated deployment to Render.

✅ Changes Included

Docker CI Pipeline

• Build and test Docker images (development + production)
• Container startup validation
• Nginx configuration testing
• Security vulnerability scanning with Trivy
• Push images to GitHub Container Registry

Deployment Automation

• Automated deployment to Render on main branch merges
• Deploy hook integration via GitHub Secrets
• Post-deployment verification checks

Branch Protection

• Enabled branch protection rules for main
• Require PR reviews before merge
• Require all CI checks to pass
• Require branches to be up to date

🔧 Configuration Required

1. GitHub Secret: Add RENDER_DEPLOY_HOOK_URL from Render dashboard
2. Render Service: Web service configured with Docker environment
3. Update URL: Replace your-app.onrender.com in deploy-render.yml with actual Render URL

🚀 Deployment Flow

Push to main → Docker CI builds image → Pushes to GHCR → Triggers Render deployment → Live ✅

✅ Testing Done

• Docker builds successfully locally
• Containers start and serve content
• CI pipeline passes on PR
• Branch protection rules active
• Ready for Render integration

📝 Next Steps After Merge

1. Add RENDER_DEPLOY_HOOK_URL secret to GitHub
2. Update Render URL in workflow file
3. Push to main to trigger first automated deployment

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⚠️ Note on Deployment

The deployment workflow is included but disabled (push trigger commented out).

To enable after merge:

1. Configure Render service
2. Add RENDER_DEPLOY_HOOK_URL secret
3. Update Render URL in workflow
4. Uncomment push trigger in deploy-render.yml
5. Push to main to activate

This allows safe merge without premature deployment attempts.

Deployed app will be live at: https://[your-service].onrender.com

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