Implement Stellar Wallet Integration Module

[mijinummi]

🧠 Concept

Add Stellar wallet connectivity support.

⚠️ Problem

Developers cannot easily test integrated contract flows.

📁 Implementation Scope

• src/integrations/wallets/stellar/

✅ Requirements

• Support Freighter wallet integration
• Enable transaction signing flows

🎯 Acceptance Criteria

• Wallet integration functional

[BigElv]

@BigElv has applied to work on this issue as part of the Stellar Wave Program's 5th wave.

I’d love to work on this issue. I have experience with backend development and blockchain integrations, and I understand how missing wallet connectivity blocks end-to-end contract testing. I’ll implement the Stellar wallet integration module under src/integrations/wallets/stellar, enabling developers to connect and test integrated contract flows cleanly.

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