Add Soroban RPC client wrapper

[pragmaticAweds]

Repository

This issue belongs in Fundable-Protocol/Backend under indexer/.

Migrated from Fundable-Protocol/stellar_indexer#9.

Context

Domain and poller code should not construct Soroban RPC clients directly. A shared wrapper keeps configuration and SDK usage consistent.

Scope

• Add Stellar/Soroban SDK dependency if not already present
• Create RPC client factory in common
• Read RPC URL and network config from validated config
• Add tests around client configuration boundaries

Out of Scope

• Unrelated package work
• Docker, CI, or deployment work unless named in scope
• Broad refactors outside the touched package

Acceptance Criteria

• Scope items are complete
• Relevant tests are added or updated
• Documentation is updated when needed
• bun run type-check passes
• bun run test passes
• bun run lint passes
• bun run indexer:type-check passes
• bun run indexer:test passes
• bun run indexer:lint passes

Dependencies

• Add environment config loader and validation #21

Suggested Files or Packages

• indexer/common/src/rpc/
• package.json
• bun.lock

[ayomideadeniran]

@ayomideadeniran has applied to work on this issue as part of the Stellar Wave Program's 6th 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)

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

🧑‍💻 @ayomideadeniran: 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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[drips-wave]

This issue has been completed by @ayomideadeniran as part of the Stellar Wave Program's 6th Wave 🥳

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