Add a per-org configurable retention and purge job for soft-deleted vaults and milestones

[1nonlypiece]

📌 Description

Vaults and milestones support soft-delete (see the soft-delete migrations), but
soft-deleted rows accumulate forever. There is no retention policy or purge
job to hard-delete rows past a per-org retention window, which bloats tables and
keeps data longer than a tenant's compliance policy allows.

This issue adds a configurable retention window and a safe purge job for
soft-deleted vault and milestone rows.

Goal: hard-purge soft-deleted vaults/milestones past a per-org retention
window, in bounded batches, with an audit record.

🎯 Requirements and Context

• Retention window must be configurable per org with a safe default.
• Purge must be batched and bounded, and must cascade correctly to children.
• Each purge batch must write an audit-log summary (count, org, window).
• Must never purge rows that are not soft-deleted.

🛠️ Suggested Execution

1. Fork the repo and create a branch

git checkout -b feature/soft-delete-retention-purge

2. Implement changes

• Add purge logic to src/services/vault.service.ts.
• Register a job in src/jobs/handlers.ts with a type in src/jobs/types.ts.
• Document the policy in docs/multi-tenancy.md.

3. Test and commit

• Add src/tests/vault.retentionPurge.test.ts run with bun test.
• Cover edge cases: window not yet elapsed, cascade to milestones, non-deleted
  rows untouched, and audit record written.

Example commit message

feat: per-org retention purge job for soft-deleted vaults

✅ Guidelines

• Minimum 95% test coverage on the new/changed lines.
• Clear, reviewer-friendly documentation.
• No regressions on existing soft-delete behaviour.
• Timeframe: 96 hours.

🏷️ Labels

type-feature · area-backend · type-testing · MAYBE REWARDED · GRANTFOX OSS · OFFICIAL CAMPAIGN

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[akinerin]

@akinerin has applied to work on this issue as part of the Stellar Wave Program's 6th wave.

Assign me to this task, I can handle it quickly

ℹ️ Repo Maintainers: To accept this application, review their application or assign @akinerin to this issue.

[drips-wave]

Congratulations, @akinerin! 🎉 Your application was accepted by the repo's maintainers, and the issue is due on June 30, 2026.

🧑‍💻 @akinerin: Please resolve the issue such that the repo's maintainers have enough time to review your contribution before the due date. You'll earn Points for completing the issue on-time, which will make you eligible for a share of the Stellar Wave Program's reward pool.

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