Implement soft delete for newsletter subscribers

[hman38705]

Issue 107: Implement soft delete for newsletter subscribers

Area: Backend
Priority: Medium
Files: services/api/src/newsletter.rs, services/api/src/db.rs

Problem

Subscriber deletion is hard delete. GDPR deletion requests cannot be audited.

Acceptance Criteria

• Deleted subscribers are marked with deleted_at timestamp\n- Soft-deleted records are excluded from queries\n- Hard delete is available for GDPR compliance\n- Audit log records deletion events

[mikevill20]

@mikevill20 has applied to work on this issue as part of the Stellar Wave Program's 4th wave.

Hello maintainer, please assign this issue to me. thanks

ℹ️ Repo Maintainers: To accept this application, review their application or assign @mikevill20 to this issue.

[famvilianity-eng]

@famvilianity-eng has applied to work on this issue as part of the Stellar Wave Program's 4th wave.

i can add this function i am familiar with this

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

[drips-wave]

Congratulations, @famvilianity-eng! 🎉 Your application was accepted by the repo's maintainers, and the issue is due on April 29, 2026.

🧑‍💻 @famvilianity-eng: 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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[drips-wave]

This issue has been completed by @famvilianity-eng as part of the Stellar Wave Program's 4th Wave 🥳

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