[FEAT] ci: Setup base GitHub Actions pipeline with code linting

[MikeNovikoff]

Description

We need an automated CI/CD pipeline to ensure code quality from day one. For Week 1, we need a baseline GitHub Actions workflow that triggers on pushes and pull requests to the main branch, running a linter to catch syntax errors early.

To do

• Create .github/workflows/main.yml.
• Configure triggers for push and pull_request on main.
• Set up Python 3.11 environment with dependency caching.
• Integrate flake8 for syntax and style checking.

Notes

• Keep the pipeline lightweight for now. We will add pytest and Docker build steps in later weeks.
• Ensure the workflow fails if critical syntax errors are found.

Acceptance Criteria

• GitHub Actions workflow file exists in the correct directory.
• Pipeline runs automatically on PR creation.
• Linter successfully checks the codebase.
• A green checkmark appears on successful PRs.