Expand description
PostgreSQL implementation of ContractorEvaluationRepository (Story
3.9 — FR34 FR35 INV-21 INV-24).
All sqlx::Error paths are wrapped in AppError::Database(_) — no
Result<_, String> debt (CRITICAL.md #4 / #555).
Evaluations are append-only: only save writes new rows. The DB
trigger contractor_eval_no_mutation (cf. migration 20260605070000)
blocks any UPDATE / DELETE at the SQL boundary, so a misbehaving caller
cannot tamper with the audit trail.