Add shared helper for parsing comma-separated query values

[aniokedianne]

Summary
Add shared helper for parsing comma-separated query values

Scope

• add reusable parser for comma-separated query strings\n- handle trimming, dedupe, and empty values consistently\n- use helper in relevant list/filter endpoints

Acceptance Criteria

• scoped change is implemented with no unrelated file churn
• docs/tests are updated where applicable
• contributor can validate the outcome locally

Contributor coordination: if you pick this up, reach out in Telegram for updates or clarification: https://t.me/accesslayerorg

[nonsobethel0-dev]

@nonsobethel0-dev has applied to work on this issue as part of the Stellar Wave Program's 4th wave.

Please assign this issue to me

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[bamiebot-maker]

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

kindly assign this issue to me

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[drips-wave]

Congratulations, @nonsobethel0-dev! 🎉 Your application was accepted by the repo's maintainers, and the issue is due on April 29, 2026.

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[drips-wave]

This issue has been completed by @nonsobethel0-dev as part of the Stellar Wave Program's 4th Wave 🥳

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