ge-hch.5.15.15: add risk scorer tests

[SorraTheOrc]

Summary

• add coverage for pacing risk elevation on long exposition branches
• enforce deterministic scoring across 10 calls and confidence-based thresholds
• document targeted test runs for director risk scorer

Testing

• npm test --silent -- tests/unit/director.test.js (fails overall due to start-server-and-test arg requirement; director suite passes)
• npx jest tests/unit/director.test.js --runInBand