fix(docker): include git so image can scaffold templates

[ulises-jeremias]

Summary

The published Docker image installs the CLI but not git. Scaffolding fails with:

CpaError: git executable not found

docs/TROUBLESHOOTING.md documents Docker as a full install path:

docker run --rm -v "${PWD}:/app" -w /app ulisesjeremias/create-awesome-python-app my-app

Smoke distribution only checks --version / --help, so this gap was not caught.

Acceptance

• Dockerfile installs git (and needed CA certs) before the CLI
• docker run ... --template fastapi-starter --addons github-setup --no-interactive --no-install ... succeeds
• Rebuild/publish image for current release (0.2.5) via workflow_dispatch
• Optionally extend smoke-distribution Docker job with a minimal scaffold smoke