ci: add GitHub Actions workflow and CI badges

[MSeyyidDev]

Summary

Adds a GitHub Actions workflow that runs the existing test suite on every push and pull request, plus status badges in the README.

Technical details

• New workflow at .github/workflows/ci.yml.
• Installs the package with pip install -e ., runs pytest, then smoke-tests the CLI (generate +
  eport).
• pip / npm dependencies are cached for fast subsequent runs.
• Uses the auto-provided GITHUB_TOKEN only; no custom secrets required.
• Read-only permissions: contents: read to follow least-privilege defaults.

Testing notes

• The workflow runs the same suite that passes locally (60 pytest tests).
• Triggers on push to main and on every PR targeting main.
• Manually re-runnable from the Actions tab.

Next steps

• Add a coverage report (e.g. pytest --cov + Codecov) and a coverage badge.
• Wire a release / deploy job once a hosting target is chosen.
• Add Dependabot config to keep dependencies fresh.