Add CI/CD pipeline with GitHub Actions

[Edmon02]

Description

Set up a comprehensive CI/CD pipeline using GitHub Actions.

Tasks

• Lint and format check (Ruff)
• Unit tests with pytest (Python 3.10, 3.11, 3.12, 3.13)
• Type checking with pyright/mypy
• Test coverage reporting with Codecov
• Notebook validation (nbval or papermill dry-run)
• Auto-publish to PyPI on release tags
• Dependabot configuration for dependency updates

Files to Create

• .github/workflows/ci.yml
• .github/workflows/release.yml
• .github/dependabot.yml