Detect Expensive SLOAD Operations

# 🧠 Concept  
Detect repeated SLOAD-heavy logic.

## ⚠️ Problem  
Frequent SLOAD usage increases gas consumption.

## 📁 Implementation Scope  
- `rules/optimization/storage/`

## ✅ Requirements  
- Identify repeated SLOAD operations  
- Suggest caching strategies  

## 🎯 Acceptance Criteria  
- [ ] Expensive SLOAD patterns flagged  