feat: implement SoroSave CLI tool (Issue #36)

[Nandu-kannan]

Bounty Submission: SoroSave SDK CLI Tool (Issue #36)

Bounty Issue: #36

What I built
A complete Node.js CLI tool built with Commander.js that allows users to interact with the SoroSave protocol directly from their terminal.

Commands Implemented

• create-group: Initialize a new savings group on-chain.
• join-group: Participate in an existing group.
• contribute: Submit contributions for the current round.
• get-group: Fetch detailed group status and metadata.
• list-groups: List all groups a specific public key is participating in.

Technical Highlights

• Stellar SDK Integration: Seamless handling of keys, networks, and transaction signing.
• Flexible Output: Supports human-readable text and machine-readable JSON (via --json).
• Configuration: Uses env vars (SOROSAVE_SECRET) or CLI flags.

Reviewer requirements checklist

1. Add CLI entry point using commander or yargs ✅
2. Commands: create-group, join-group, contribute, get-group, list-groups ✅
3. Package bin configuration ✅

[big14way]

@Nandu-kannan theres a conflict in the pipeline please fix