[BE-120] Unit tests for the risk-assessment module

[mftee]

Overview

backend/src/risk-assessment/ has 3 files and no tests. Risk scoring is the product's core intelligence — a wrong score on a land document could contribute to a real dispute, so its logic deserves explicit, example-based verification.

Tasks

• Test each risk heuristic in isolation with inputs that should and should not trigger it.
• Test score aggregation across multiple flags, and verify the score stays within its defined range.
• Test boundary cases: no flags, all flags, and conflicting signals.
• Test that scoring is deterministic — the same document must always yield the same score.
• Document what each risk flag means and what evidence triggers it, as part of the test names.
• Target ≥80% coverage — this module warrants a higher bar than most.

Acceptance Criteria

• Every risk heuristic has explicit positive and negative test cases.
• Scores are proven deterministic and bounded.
• npm run test -- risk-assessment passes at ≥80% coverage.

Notes for Contributors

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