test(transactions): cover history route integration

[h1065153539-create]

Summary

• Adds supertest integration coverage for GET /api/transactions/history in tests/routes/transactions.test.ts.
• Covers deterministic ordering, bond filters, limit/cursor pagination, empty results, validation envelopes, repository failure handling, and 401/403 authorization cases.
• Decodes opaque cursors during query validation before passing them to SettlementsRepository.findManyPaginated.
• Protects transaction history reads with the existing trust:read API-key scope.

Closes #472

Validation

• npm test -- transactions passed: 1 test file, 10 tests.
• git diff --check -- src/routes/transactions.ts src/schemas/transactions.ts tests/routes/transactions.test.ts passed.
• npm run test:coverage -- transactions ran the focused tests successfully, then exited non-zero because the repo applies global thresholds to all src/**/*.ts and src/sdk/** during a filtered run.
• File-level coverage from coverage/coverage-final.json:
  • src/routes/transactions.ts: 100% statements, 100% branches, 100% functions, 100% lines.
  • src/schemas/transactions.ts: 100% statements, 90% branches, 100% functions, 100% lines.
• npm run lint is blocked before linting by missing src/observability/eslint-plugin-logger-schema.js imported from eslint.config.js.
• npm run build is still blocked by existing repo-wide TypeScript errors, but no transactions-related errors remain after this change.