Python Web App CI/CD Pipeline

Problem/Feature Description

A team has a Python web application built with FastAPI. They need a GitHub Actions CI/CD workflow to automate their development pipeline. The application uses pytest for testing, ruff for linting, and mypy for type checking. Dependencies are managed with pip and defined in requirements.txt.

The workflow should:

1. Run on pushes to main and on pull requests targeting main
2. Lint the code
3. Run type checking
4. Run the test suite
5. Deploy the application (for now, just a placeholder deploy step that echoes "Deploying to production")

The deployment requires a DEPLOY_API_KEY credential and a DEPLOY_URL endpoint.

Output Specification

Produce:

• output/.github/workflows/ci.yml — The complete GitHub Actions workflow file

The workflow should be complete and ready to use. No placeholders or TODO comments (except the deploy step itself which is intentionally a placeholder).