engine 0.1.0 — initial self-hosted release

Self-hosted badge rendering engine via Docker:
- 30+ badge providers (npm, GitHub, PyPI, Docker Hub, etc.)
- SVG, PNG, and JSON output
- GitHub token pool with OAuth
- PostgreSQL for token storage + memo badges
- Health check at /api/health

docker pull ghcr.io/jal-co/shieldcn/engine:0.1.0