Add cursor-based pagination to the key holders list endpoint

[Chucks1093]

Summary

The key holders list endpoint returns all holders in a single response, which will degrade under load as holder counts grow. Cursor-based pagination using the holder wallet address as the cursor should be introduced.

Scope

• Add cursor and limit query parameters to GET /keys/:keyId/holders
• Default limit to 20, maximum 100
• Return a nextCursor field in the response if more records exist
• Use an index on (keyId, walletAddress) to support efficient keyset queries
• Return an empty holders array with no nextCursor when no results exist

Acceptance Criteria

• First page returns up to limit records with a nextCursor
• Passing nextCursor returns the next page starting after the cursor
• Last page returns no nextCursor
• limit above 100 is clamped to 100
• Response order is stable across pages

ETA: 12 hours

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Coordinate on Telegram

[VikkyFame01]

@VikkyFame01 has applied to work on this issue as part of the Stellar Wave Program's 8th wave.

Hi Maintainer, I’ve carefully reviewed the issue and have a clear understanding of the required changes. I’m ready to get started and would be glad to implement a clean, reliable solution that fully meets the acceptance criteria.

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[francisprecious061]

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Hello maintainer, i'd love to fix this... Assign me.

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[samkay-ops]

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Hi team,
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I have strong experience with TypeScript, NestJS, and Soroban smart contracts. I will deliver clean, tested code following the acceptance criteria.
Ready to start immediately.
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samkay-ops

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[Hamzasaheed]

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[JamesVictor-O]

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Hello! I’d love to take on this issue. I’ve reviewed the requirements and have a clear path forward for the implementation. I estimate I can have a PR ready within about 3 hours of being assigned. Could you please assign this to me?

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[Jessicaayegh]

@Jessicaayegh has applied to work on this issue as part of the Stellar Wave Program's 8th wave.

Hi maintainer! I’d love to work on this issue if it’s still available. I have a good understanding of the requirements and would be happy to implement the solution. Thanks for considering my request!

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Congratulations, @JamesVictor-O! 🎉 Your application was accepted by the repo's maintainers, and the issue is due on August 31, 2026.

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[grantfox-oss]

🎉 This issue has been marked as completed on GrantFox as part of the Third Campaign campaign!

@JamesVictor-O's PR #789 was approved and merged by @Chucks1093.

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👏 Great work, @JamesVictor-O! Keep contributing to accesslayerorg.

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