F-11 (Medium): Test the production repository against real SQLite

[adamburmister]

Finding

F-11 (Medium) from the ledger audit: the production SqlStorageRepository — where atomicity (transactionSync), rollback, unique-constraint mapping, dedup-race recovery, and SQL date-range semantics actually live — had zero tests in this repo. The 78-test suite ran exclusively against the in-memory double, and the double demonstrably diverged: audit probe P7 pushed onto a returned entry.debitAmounts (runtime arrays; readonly is compile-time only) and the tampered line appeared in subsequent allEntries() reads — the double aliased its internal arrays, while production re-hydrates per query and is immune.

Why it matters: a refactor that, say, moved the idempotency-key insert outside the transaction block would ship with every unit test green. Trusting an external demo app to exercise rollback paths is not a control.

Fix

• test/helpers/node-sql-storage.ts: a DurableObjectStorage stand-in over Node's built-in node:sqlite (no new dependencies), exposing exactly the surface the repository uses — sql.exec(...) with toArray()/one() cursors and transactionSync implemented via SAVEPOINT. node:sqlite enforces foreign keys by default, matching DO storage.
• sqlite-repository.spec.ts drives the real repository through the Ledger facade and directly:
  • account creation + duplicate rejection via the actual DB unique index
  • posting by account name, balances, SQL date-range filtering, balanceByType
  • trial balance zero across types including contra accounts
  • entry hydration (getEntry, entriesForAccount, amountsForAccount, getEntryByKey)
  • idempotency-key retry dedup
  • atomicity proof: a balanced payload whose second amount row violates the FK constraint → RepositoryError and zero rows in pluts_entries/pluts_amounts — the rollback the design promises, now verified on every CI run
• In-memory aliasing fixed: InMemoryRepository.toEntry copies its line arrays (regression test included), so the double matches production semantics.

All six production-repository tests passed on first run — the existing transaction code is correct; it just had no in-repo proof.

Testing

Full suite: 85 passed (78 base + 7 new). tsc --noEmit and biome check clean. The aliasing test was written first and watched fail against the unfixed double.

Note: shares test/types/node-sqlite.d.ts with #4/#5/#7/#8 (identical content — merges cleanly in any order).

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