smart contract: Implement user registry username reservation locking fee

[ONEONUORA]

Description

Deduct small lock fee during username reservation that is refunded upon profile completion.

Files to Edit/Create

• contracts/contracts/user_registry/src/lib.rs

Acceptance Criteria

• Transfer reservation fee to escrow storage and release on activation.

Guidance / Hints

Use Naira token contract instance.

[ASIDISG]

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

Hi buddy, could you please let me work on this issue? I am interested.

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

🧑‍💻 @ASIDISG: 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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This issue has been completed by @ASIDISG as part of the Stellar Wave Program's 8th Wave 🥳

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