Claim Approval Decision Repository

Low complexity with three clearly defined interfaces, this component can be delivered quickly and in parallel with other data-layer work. The primary integration dependency is the expense_claims table and claim_events table schema being finalised, as this repository links decisions to both. The `getApprovedClaimsForExport` query requires agreement with the accounting and reporting stakeholders on the exact fields, date range filter format, and whether the export scope is per organisation or per programme — this requirements clarification should happen before development begins to avoid rework. Testing should include verifying that `saveDecision` is idempotent or appropriately rejects duplicate decisions for the same claimId, and that export queries correctly scope results to the requesting organisation.

This component persists records to a `claim_decisions` (or equivalent) table that holds a foreign key to `expense_claims.id` and captures `coordinator_id`, `decision` (enum: approved | rejected), `comment` (nullable), and `decided_at` timestamp. The `saveDecision` method should enforce a unique constraint on `claim_id` to prevent duplicate decision records, returning a conflict error if a decision already exists rather than silently overwriting. `getDecision` is a simple primary key lookup and should return null rather than throwing when no decision exists, to allow callers to distinguish between an undecided claim and an error. `getApprovedClaimsForExport` must join to the parent `expense_claims` table to assemble the full export record including claim metadata; parameterise the date range against `decided_at` rather than `submitted_at` to correctly capture the approval event timing for financial period alignment.