feat: stellar settlement, audit, notifications, and versioning

[lynaDev2]

Closes #350
Closes #351
Closes #352
Closes #353

Summary

This PR introduces core infrastructure upgrades for Stellar bridge reliability, observability, and cross-chain safety.

---

Contract Version Resolver (#350)

• Tracks deployed Soroban contract versions
• Dynamically resolves active contracts across environments
• Prevents version mismatch failures

---

Transfer Notification Service (#351)

• Emits real-time transfer status updates
• Supports webhook and UI-based alerts
• Improves user visibility during bridge operations

---

Cross-Chain Settlement Verifier (#352)

• Verifies completion of cross-chain settlements
• Detects mismatches and incomplete transfers
• Ensures consistency across chains

---

Transfer Audit API (#353)

• Stores detailed Stellar transfer audit logs
• Provides searchable audit endpoints
• Enables developer debugging and traceability

---

Testing & Validation

• Unit tests for version resolution logic
• Notification emission tests
• Audit log storage and retrieval tests
• Settlement verification edge cases covered

---

Impact

• Improved cross-chain reliability
• Better observability of transfers
• Stronger audit and compliance tracking
• Reduced risk of inconsistent settlements
  "

[drips-wave]

@lynaDev2 Great news! 🎉 Based on an automated assessment of this PR, the linked Wave issue(s) no longer count against your application limits.

You can now already apply to more issues while waiting for a review of this PR. Keep up the great work! 🚀

Learn more about application limits