Implement Structured Logging

# 🧠 Concept
Standardize application logs.

## ⚠️ Problem
Unstructured logs are difficult to search and analyze.

## 📁 Implementation Scope
- src/modules/logging/

## ✅ Requirements
- JSON logging
- Context support
- Correlation IDs

## 🎯 Acceptance Criteria
- [ ] Structured logs enabled
- [ ] Correlation IDs generated
- [ ] Log format documented