[Backend] Implement Stale Task Detection and Cleanup Workflow for Backend Indexes

[ayomideadeniran]

Contributor Focus: [Data Hygiene] Keep backend task views from accumulating outdated or misleading records over time
ETA: 2 days

Context

Secondary backend stores and indexes can accumulate stale task views if cleanup rules are weak.

Problem

Outdated records confuse operators and can pollute analytics or admin tooling.

Task Breakdown

1. Define what counts as stale in backend read models.
2. Add a detection and cleanup strategy that is safe and reviewable.
3. Preserve enough history for debugging before removing or archiving records.
4. Expose cleanup activity through logs or metrics.
5. Document retention and cleanup tradeoffs.

Acceptance Criteria

• Stale indexed task data can be detected and cleaned up safely.
• Cleanup rules are explicit.
• Useful history is not destroyed blindly.
• Operators can understand what the cleanup process changed.

[Favourejiro]

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

Hello maintainers, I would like to work on this issue because I am well-experienced in solving these types of issues."

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[DeePrincipal-dev-lang]

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

Hello Maintainer, I'm a prompt engineer and I would like to work on this issue because I am reliable, detail-oriented, and able to complete tasks accurately and on time. I’m confident I can deliver quality results.

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[drips-wave]

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