[Phase 0.1.1] Set up GitHub Actions CI pipeline

[richard-devbot]

Phase

Phase 0 — Foundations | Track 0.1 — CI/CD Pipeline | Priority: P0

Summary

Set up a GitHub Actions CI pipeline that runs on every PR against main.

What

• Create .github/workflows/ci.yml
• Run pytest (unit + existing tests)
• Run ruff linter
• Fail the PR if either check fails
• Cache pip dependencies for speed

Why

No CI exists today. Every subsequent security fix, guardrail, and performance optimization needs automated validation. This is the foundation for all other work.

Acceptance Criteria

• .github/workflows/ci.yml exists and triggers on PRs to main
• pytest runs all tests in tests/
• ruff lint passes
• Pipeline completes in under 5 minutes
• Badge added to README

References

• GitHub Actions for Python
• Design Doc: docs/plans/2026-03-29-security-ai-guardrails-performance-design.md

Blocked By

None — this is the first issue to implement.

Blocks

All Phase 0.1.x issues (0.1.2 through 0.1.5) build on this workflow.