Jenkins reference pack

Goal

Run the same first-proof lane in Jenkins scripted/declarative jobs.

Pipeline contract

1. Checkout repository.
2. Create/activate .venv.
3. Install dependencies.
4. Run make first-proof-verify.
5. Archive build/first-proof/*.

Operator outputs

• first-proof-summary.json
• weekly-threshold-check.json
• phase3-dependency-radar-*.json (optional governance lane)