Implement Soroban Contract Call Trace Analyzer

# 🧠 Concept  
Analyze execution traces for Soroban contract calls.

## ⚠️ Problem  
Developers lack low-level execution visibility.

## 📁 Implementation Scope  
- `src/tracing/stellar/`

## ✅ Requirements  
- Capture execution traces  
- Display nested call flow  

## 🎯 Acceptance Criteria  
- [ ] Trace analyzer implemented  