feat: add PostgreSQL recovery rehearsal

[seonghobae]

Summary

• add a forward audit-correlation index migration
• add a disposable native PostgreSQL backup/restore rehearsal with measured tenant skew, RLS preservation, and forward-migration assertions
• update the operational readiness, ADR, PRD, TRD, changelog, README, and gap register

Real local evidence

• PostgreSQL 18.4
• 1,000 anonymized audit events across tenants with 900/100 distribution and 9.00 skew ratio
• dump/restore preserved the tenant distribution, 16 policies, and 16 forced-RLS relations
• forward 0002_audit_correlation_index.sql applied successfully

Verification

• shellcheck scripts/postgres_recovery_rehearsal.sh
• PGHOST=127.0.0.1 PGPORT=5432 PGUSER=$(id -un) scripts/postgres_recovery_rehearsal.sh
• cargo +1.97.1 fmt --all -- --check
• cargo +1.97.1 test --workspace --all-targets --locked
• cargo +1.97.1 clippy --workspace --all-targets --locked -- -D warnings
• RUSTDOCFLAGS="-D warnings" cargo +1.97.1 doc --workspace --no-deps --locked
• actionlint, docs contract, and git diff --check

Gate

This PR is intentionally stacked on PR #17 exact head 80379bc. It remains subject to an independent current-head review, required Checks, and the protected merge rules. No self-approval, merge, or protection bypass is requested.

[coderabbitai]

Important

Review skipped

Auto reviews are disabled on base/target branches other than the default branch.

Please check the settings in the CodeRabbit UI or the .coderabbit.yaml file in this repository. To trigger a single review, invoke the @coderabbitai review command.

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Pro Plus

Run ID: a0a071fb-1975-407e-beef-a3e9fbf72e82

You can disable this status message by setting the reviews.review_status to false in the CodeRabbit configuration file.

Use the checkbox below for a quick retry:

• 🔍 Trigger review

---

Thanks for using CodeRabbit! It's free for OSS, and your support helps us grow. If you like it, consider giving us a shout-out.

❤️ Share

• X
• Mastodon
• Reddit
• LinkedIn

_{Comment @coderabbitai help to get the list of available commands.}

[seonghobae]

@opencode-agent Review only the exact current head 37382cf against base 80379bc for PR #18. Do not update branches, approve, merge, or bypass protection. Check the forward migration, SQLx embedded-migration behavior, disposable PostgreSQL rehearsal cleanup/connection safety, and whether the documented evidence stays distinct from production-readiness claims.

[seonghobae]

@opencode-agent Review only the exact current head f0a5e55 on PR #18 against base 80379bc. The head adds the required PostgreSQL smoke assertion for audit_event_record_tenant_correlation_idx. Do not update branches, approve, merge, or bypass protection; re-check migration lock/SQLx behavior, rehearsal cleanup/connection safety, and evidence boundaries.