chore: refactor logging module, update genesis timestamp, remove model relationships, and reorganize routers
- Rename logging.py to logger.py and update import paths in poa.py and main.py
- Update devnet genesis timestamp to 1766828620
- Remove SQLModel Relationship declarations from Block, Transaction, and Receipt models
- Add SessionDep type alias and get_session dependency in coordinator-api deps
- Reorganize coordinator-api routers: replace explorer/registry with exchange, users, marketplace
- Add Prometheus metrics for marketplace API throughput and error rates with new dashboard panels
- Implement confidential transaction models with encryption support and access control
- Add key management system with registration, rotation, and audit logging
- Create services and registry routers for service discovery and management
- Integrate ZK proof generation for privacy-preserving receipts
- Add metrics instru
