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

migrate_to_postgres.sh

@@ -0,0 +1,67 @@
+#!/bin/bash
+
+# PostgreSQL数据迁移脚本
+# 用于将SQLite数据迁移到PostgreSQL
+
+set -e
+
+echo "🔄 开始数据库迁移..."
+
+# 检查PostgreSQL服务是否运行
+echo "📋 检查PostgreSQL服务状态..."
+if ! docker-compose ps postgres | grep -q "Up"; then
+    echo "⚠️  PostgreSQL服务未运行，正在启动..."
+    docker-compose up postgres -d
+    echo "⏳ 等待PostgreSQL启动..."
+    sleep 10
+fi
+
+# 检查连接
+echo "🔌 测试数据库连接..."
+if ! docker-compose exec postgres pg_isready -U nofx; then
+    echo "❌ 无法连接到PostgreSQL，请检查服务状态"
+    exit 1
+fi
+
+echo "✅ PostgreSQL连接正常"
+
+# 执行数据迁移
+echo "📦 执行数据迁移..."
+if docker-compose exec -T postgres psql -U nofx -d nofx -f /tmp/migrate_actual_data.sql; then
+    echo "✅ 数据迁移成功！"
+else
+    echo "⚠️  执行迁移脚本..."
+    # 将本地文件复制到容器并执行
+    docker cp migrate_actual_data.sql $(docker-compose ps -q postgres):/tmp/migrate_actual_data.sql
+    docker-compose exec postgres psql -U nofx -d nofx -f /tmp/migrate_actual_data.sql
+    echo "✅ 数据迁移完成！"
+fi
+
+# 验证数据
+echo "🔍 验证迁移结果..."
+docker-compose exec postgres psql -U nofx -d nofx -c "
+SELECT 'Table Statistics:' as info;
+SELECT 
+    schemaname,
+    tablename, 
+    n_tup_ins as inserts,
+    n_tup_upd as updates,
+    n_tup_del as deletes,
+    n_live_tup as live_rows
+FROM pg_stat_user_tables 
+ORDER BY tablename;
+"
+
+echo ""
+echo "🎉 数据库迁移完成！"
+echo ""
+echo "📋 后续步骤："
+echo "1. 启动应用: docker-compose up"
+echo "2. 验证功能: 访问 http://localhost:3000"
+echo "3. 备份原SQLite: mv config.db config.db.backup"
+echo ""
+echo "🔧 如需回滚到SQLite:"
+echo "1. 停止服务: docker-compose down"
+echo "2. 删除环境变量: unset POSTGRES_HOST"
+echo "3. 恢复备份: mv config.db.backup config.db"
+echo "4. 重启: docker-compose up"