feat: Implement Soroban RPC client with retry logic

[cypriannwokolo2-creator]

Description

Build a robust Soroban RPC client for the backend with retry logic, timeout handling, and error classification.

Requirements

• Implement Soroban RPC client wrapper
• Add retry logic with exponential backoff
• Add timeout handling (30s default)
• Classify Soroban errors into domain errors

Acceptance Criteria

• Client handles network failures gracefully
• Retry logic with exponential backoff
• Timeout handling prevents hanging requests
• Error classification maps Soroban errors to domain errors

Priority

High

[baling-1]

@baling-1 has applied to work on this issue as part of the Stellar Wave Program's 8th wave.

hey maintainer kindly assign this to me

ℹ️ Repo Maintainers: To accept this application, review their application or assign @baling-1 to this issue.

[UbAh-Eb]

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

Hi, I'm a maintainer assign this to me
I've looked at the problem and I'll love to resolve it

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

[linesofcodes0-cloud]

@linesofcodes0-cloud has applied to work on this issue as part of the Stellar Wave Program's 8th wave.

I'm a full-stack developer and I'd like to take this issue.
I understand the requirements and will follow the existing project structure, keep the implementation clean, and include proper tests where applicable.

ETA: 1–3 days (depending on scope)

ℹ️ Repo Maintainers: To accept this application, review their application or assign @linesofcodes0-cloud to this issue.

[drips-wave]

Congratulations, @linesofcodes0-cloud! 🎉 Your application was accepted by the repo's maintainers, and the issue is due on August 31, 2026.

🧑‍💻 @linesofcodes0-cloud: 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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