feat: migrate from SQLite to PostgreSQL + Redis architecture

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

go.mod

@@ -9,7 +9,8 @@ require (
 	github.com/golang-jwt/jwt/v5 v5.2.0
 	github.com/google/uuid v1.6.0
 	github.com/gorilla/websocket v1.5.3
-	github.com/mattn/go-sqlite3 v1.14.16
+	github.com/lib/pq v1.10.9
+	github.com/mattn/go-sqlite3 v1.14.32
 	github.com/pquerna/otp v1.4.0
 	github.com/sonirico/go-hyperliquid v0.17.0
 	golang.org/x/crypto v0.42.0