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

api/server.go

@@ -21,12 +21,12 @@ import (
 type Server struct {
 	router        *gin.Engine
 	traderManager *manager.TraderManager
-	database      *config.Database
+	database      config.DatabaseInterface
 	port          int
 }
 
 // NewServer 创建API服务器
-func NewServer(traderManager *manager.TraderManager, database *config.Database, port int) *Server {
+func NewServer(traderManager *manager.TraderManager, database config.DatabaseInterface, port int) *Server {
 	// 设置为Release模式（减少日志输出）
 	gin.SetMode(gin.ReleaseMode)