docs(deployments): add AWS EC2 + Docker deployment example (#390)

[vaquarkhan]

• Dockerfile + docker-compose for local development parity
• FastAPI server wrapping the Burr counter application
• Production-grade Terraform with modular structure (networking + compute)
• Security: IMDSv2 enforced, EBS encryption, CIDR validation, no 0.0.0.0/0 ingress
• Environment-specific tfvars (dev/prod)
• RST docs page wired into deployment index
• 40 automated tests (structure, license headers, app logic, security checks)
• Full README with quickstart, deploy, verify, teardown, and security guidance

[Short description explaining the high-level reason for the pull request]

Changes

How I tested this

Notes

Checklist

• PR has an informative and human-readable title (this will be pulled into the release notes)
• Changes are limited to a single goal (no scope creep)
• Code passed the pre-commit check & code is left cleaner/nicer than when first encountered.
• Any change in functionality is tested
• New functions are documented (with a description, list of inputs, and expected output)
• Placeholder code is flagged / future TODOs are captured in comments
• Project documentation has been updated if adding/changing functionality.

[vaquarkhan]

Testing performed:

All 40 pytest tests pass (
test_ec2_docker_example.py
)
terraform fmt -check -recursive clean
terraform init -backend=false && terraform validate passes
Deployed to real AWS (us-east-1, t3.micro): terraform apply provisions 5 resources
Docker builds on-instance in ~2 min, container starts with --restart=unless-stopped
Verified via SSM:
curl localhost:8000/health returns {"status":"ok"}
curl -X POST localhost:8000/run -d '{"number":3}' returns {"counter":3,"counter_limit":3,"__SEQUENCE_ID":3,"__PRIOR_STEP":"result"}
terraform destroy cleanly removes all resources
All files have Apache license headers, no 0.0.0.0/0 in ingress rules, IMDSv2 enforced, EBS encrypted