feat(routes-f): tip refund request

[davedumto]

Summary

Allow a tipper to request a refund for a recent tip (creator approval required).

Requirements

• POST { tip_id, tipper_id, reason } -> { request_id, status: pending }
• POST /resolve { request_id, decision: approve|deny, creator_id, note? }
• Reject tips older than 24h with 400
• Tests cover request, approval, denial, expiry

Scope Constraint - READ BEFORE STARTING

All files for this task must live inside app/api/routes-f/. This includes the route handler, helpers/utilities, types, and tests. Do NOT modify, import from, or add files to lib/, utils/, types/, components/, or anywhere else outside app/api/routes-f/. If you need shared logic, duplicate it inside your subfolder. Keeping everything scoped to this folder is intentional - it keeps these tasks independent and mergeable in any order.

Product Context

StreamFi is a blockchain-powered live streaming platform. Streamers broadcast via Mux, viewers tip in Stellar XLM/USDC, creators have stream privacy modes (public/unlisted/subscribers-only). Build these issues as practice implementations - use realistic data shapes that match the platform domain, but do not import from the real app code.

[AlphaTechini]

@AlphaTechini has applied to work on this issue as part of the Stellar Wave Program's 6th wave.

I would like to work on this issue

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

@davedumto kindly assign

[JoyLight00]

@JoyLight00 has applied to work on this issue as part of the Stellar Wave Program's 6th wave.

I'll take #1048.

Tip refund request endpoint inside routes-f/:

POST / creates pending refund request

POST /resolve approves/denies (creator only)

Reject tips >24h old

Tests for request, approval, denial, expiry

ETA: 2.5 hours. Assign me.

ℹ️ Repo Maintainers: To accept this application, review their application or assign @JoyLight00 to this issue.

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Congratulations, @JoyLight00! 🎉 Your application was accepted by the repo's maintainers, and the issue is due on June 30, 2026.

🧑‍💻 @JoyLight00: 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 @JoyLight00 as part of the Stellar Wave Program's 6th Wave 🥳

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