Infrastructure: GitHub Actions CI (format, lint, quality gates)

[rosspeili]

Summary

Add GitHub Actions workflows and supporting config so pull requests get automated feedback on Python quality.

Tooling (proposed)

Tool	Role
Black	Formatting (check on PR)
Flake8	PEP 8 and selected style rules
Pylint	Static analysis with scoped config for the legacy monolith
isort	Optional, if not covered by Black
pytest	Optional, phased when tests/ exists

Deliverables

• .github/workflows/ (e.g. ci.yml on pull_request and push to default branch)
• Root or pyproject.toml config for Black, Flake8, Pylint
• Excludes for secrets and local-only paths (kun.py, .venv, outputs/, etc.)

Scope boundaries

• No boot, biometric, or live API jobs without mocks
• No full GPU stack in CI unless justified
• Use requirements.txt for dependency install intent

Acceptance criteria

• Workflow runs on PRs and shows pass/fail
• Black, Flake8, and Pylint configured with sensible excludes
• Local reproduction commands noted for the CONTRIBUTING sub-issue

Depends on

• Parent: Infrastructure: add .github directory

Related

• CONTRIBUTING sub-issue for “run checks before PR”
• File CI-only changes with enhancement or bug until custom ci labels exist