Multi-Network Environment Configuration Switcher

[Kingsman-99]

Description

The SDK is initialized with hard-coded Horizon and Soroban RPC URLs, making it cumbersome to switch between mainnet, testnet, and futurenet during development or integration testing without re-instantiating the entire client. A first-class environment switcher would provide built-in network presets, validate that the active network passphrase matches the RPC endpoint's reported passphrase, and allow runtime network swapping while in-flight requests finish cleanly.

Technical Context

Extends src/config.ts with a NetworkEnvironment enum (MAINNET | TESTNET | FUTURENET | CUSTOM) and a NetworkPreset interface mapping each value to { horizonUrl: string; rpcUrl: string; networkPassphrase: string }. The StellarSplitClient in src/client.ts gains a switchNetwork(env: NetworkEnvironment | NetworkPreset): Promise<void> method. Passphrase cross-check uses SorobanRpc.Server.getNetwork() from @stellar/stellar-sdk.

Acceptance Criteria

• switchNetwork(NetworkEnvironment.TESTNET) reconfigures internal Horizon and RPC URL references and validates the passphrase against the live RPC endpoint before accepting the switch
• Passing NetworkEnvironment.CUSTOM without a full NetworkPreset object produces a TypeScript compile-time error via function overload typing
• In-flight requests at the moment of a switch complete against the original network; requests issued after switchNetwork resolves use the new configuration
• A NetworkMismatchError (with expected and actual passphrase fields) is thrown when the live RPC passphrase does not match the preset
• Tests cover successful switch, passphrase mismatch rejection, and concurrent-request safety during the switchover window
• All CI checks (npm test, npm run build, ESLint/TypeScript) pass and the branch has no merge conflicts

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[NoahJoseph-ux]

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

Hello Maintainer, I’ve thoroughly read through the requirements and understand the expected outcome. I’d be happy to take this on if you can assign it to me

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

[drips-wave]

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

🧑‍💻 @NoahJoseph-ux: 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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