Major database migration to modernize the AI trading system:
• **Database Migration**:
- Add PostgreSQL 15 and Redis 7 services to docker-compose
- Create comprehensive PostgreSQL schema with proper indexes and triggers
- Implement DatabaseInterface for multi-database support
- Add automatic environment-based database selection
• **Infrastructure**:
- PostgreSQL: ACID transactions, better concurrency, JSON support
- Redis: High-performance caching layer (prepared for future use)
- Docker services with health checks and dependency management
- Persistent volumes for data safety
• **Code Refactoring**:
- Abstract database operations through DatabaseInterface
- Implement PostgreSQL-specific operations with proper syntax
- Update all SQL queries to support both SQLite and PostgreSQL
- Fix foreign key constraints and data type conversions
• **Migration Tools**:
- Automated data migration script from SQLite to PostgreSQL
- Complete backup and restore procedures
- One-click migration script with validation
• **Compatibility**:
- Backward compatible with existing SQLite deployments
- Environment variable driven database selection
- Preserved all existing functionality and data
🎯 Benefits: Better performance, scalability, and reliability for production deployments
