Implement Stellar Dynamic Route Scoring

# 🧠 Concept  
Score Stellar bridge routes using real-time metrics.

## ⚠️ Problem  
Static route rankings become outdated quickly.

## 📁 Implementation Scope  
- `src/scoring/routes/stellar/`

## ✅ Requirements  
- Update scores dynamically  
- Factor network conditions  

## 🎯 Acceptance Criteria  
- [ ] Dynamic route scoring implemented  