Issue 402: web3: Integrate Soroban Rust Smart Contract Client

[AlAfiz]

Description

The network layer needs a standardized way to interact with our on-chain logic deployed on the Stellar network. We need to implement a dedicated RPC client module that securely communicates with Soroban smart contracts.

Requirements

• Integrate the Soroban RPC SDK into the network core.
• Create a dedicated service class to handle contract invocation and simulation.
• Implement robust error handling for common Stellar network failures (e.g., transaction expired, insufficient fee).
• Write integration tests that invoke a simple read-only function on a deployed Testnet contract.