Fee estimation helpers per Stellar op type

[truthixify]

Extra labels: stellar, feature
Tier: S (1-2 days) | Type: feature

Context. Wraith flows submit at the min base fee, which fails during network congestion. Ship helpers that estimate a suitable inclusion fee per op type using recent ledger data.

Scope.

• estimateFee(opKind, urgency) returning a stroops value.
• Pull recent fee stats from Horizon /fee_stats.
• Cache with a short TTL (seconds).

Acceptance.

• Doc'd urgency levels (low / normal / high)
• Test with mocked Horizon fee-stats response
• Integration test on futurenet submits a tx with estimated fee

Files. src/chains/stellar/fee.ts (new), test/chains/stellar/fee.test.ts (new).

[praizeD10]

@praizeD10 has applied to work on this issue as part of the Stellar Wave Program's 7th wave.

I would like to work on this issue because accurate fee estimation is an important part of building a good developer experience when working with Stellar transactions. Providing helper functions for estimating fees across different Stellar operation types would make it easier for developers to build reliable applications while reducing duplicated logic throughout the SDK.
I would be happy to contribute a clean, well-documented implementation of fee estimation helpers that aligns with the SDK’s existing architecture and coding standards.

ℹ️ Repo Maintainers: To accept this application, review their application or assign @praizeD10 to this issue.

[drips-wave]

Congratulations, @praizeD10! 🎉 Your application was accepted by the repo's maintainers, and the issue is due on July 30, 2026.

🧑‍💻 @praizeD10: 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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