feat: add ledger backup safety workflow

confirm dcy-002 and add REQ/BAT evidence

add ledger backup/status metadata workflow

document restore as runbook/script-only guarded operation

add synthetic DB backup/restore smoke tests

docs/batches/bat-002_20260627_operational-safety-backup-restore-validation-db/index.md

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+# BAT-002: 운영 안전 백업·복구·검증 DB 워크플로우
+
+## Metadata
+- BAT ID: BAT-002
+- Profile: standard
+- Status: release-candidate
+- Source Discovery: dcy-002
+- Included REQ: REQ-002
+- Created At (KST): 2026-06-27 10:17
+- Owner: 렛저장인
+
+## Scope
+- Add metadata-only DB status, backup create/list/status helpers.
+- Expose backup/status/list/hash as additive MCP tools.
+- Keep restore execution out of MCP and document script/runbook approval path.
+- Verify with synthetic DB tests and safe restore smoke.
+- Update runtime, data-model, and interface baseline docs.
+
+## Out of Scope
+- 실제 운영 DB restore 실행.
+- 원본 운영 DB 직접 mutation.
+- 파괴적 SQLite migration 또는 대량 data rewrite.
+- 신규 금융기관 parser, CI/CD 구축, 배포 서비스화.
+
+## Documents
+- [planning.md](planning.md)
+- [design.md](design.md)
+- [implementation.md](implementation.md)
+- [verification.md](verification.md)
+
+## Notes
+- Restore is intentionally script/runbook only; no `restore_*` MCP tool should be added.
+- Evidence must remain metadata-only and exclude merchant/counterparty full dumps, raw_payload, account numbers, passwords, and source financial files.