Implement Soroban Security Regression Suite

[mijinummi]

🧠 Concept

Prevent security rule regressions across releases.

⚠️ Problem

Rule changes may unintentionally reduce detection accuracy.

📁 Implementation Scope

• tests/regression/security/stellar/

✅ Requirements

• Build regression datasets
• Validate expected findings
• Automate regression checks

🎯 Acceptance Criteria

• Regression suite implemented
• Regression checks automated