feat(sdk): implement multicall batching for read-only queries

[EDOHWARES]

Description

This PR augments the @bc-forge/sdk with batching capabilities for read-only contract queries. It addresses the overhead of sequential RPC calls when querying multiple data points (e.g., balances for a list of holders) by consolidating requests into asynchronous groupings.

Key Changes

• Batch Execution Engine: Added an internal executeBatch helper to bcForgeClient that processes arrays in configurable chunks using Promise.all.
• Native Balance Batching: Implemented getBalances(addresses[], batchSize) for efficient multi-address lookups.
• RPC Protection: Integrated batch limits (default: 10) to prevent aggressive rate-limiting from Soroban RPC endpoints.

Acceptance Criteria

• Map arrays iterating explicitly requesting Promise.all logic.
• Consolidate query limits protecting RPC configurations.
• Ensure SDK output variants format object results relative to requests.

Closes #28

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[EDOHWARES]

@p3ris0n , pls approve workflow so I confirm if it passes.