feat: 重构前后端架构，添加Go后端和Python Agent服务

- 新增 Go 语言后端服务(server/)，包含用户认证、Agent管理、数据库连接等API
- 新增 Python Agent 服务(agent/)，实现Agent核心逻辑和工具集
- 前端从原生HTML迁移到Vue.js框架(web/src/)
- 添加 Docker Compose 支持(docker-compose.yml)
- 添加项目架构文档(docs/ARCHITECTURE.md)
- 添加环境变量示例(.env.example)和本地启动脚本(start-local.ps1)

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

server/internal/config/config.go

@@ -0,0 +1,61 @@
+package config
+
+import (
+	"fmt"
+	"log"
+
+	"gorm.io/driver/mysql"
+	"gorm.io/gorm"
+	"gorm.io/gorm/logger"
+
+	"github.com/spf13/viper"
+)
+
+type Config struct {
+	Port              string
+	JWTSecret         string
+	DatabaseURL       string
+	PythonServiceURL string
+}
+
+func Load() *Config {
+	viper.SetConfigName("config")
+	viper.SetConfigType("yaml")
+	viper.AddConfigPath("./config")
+	viper.AddConfigPath("../config")
+	viper.AddConfigPath("../../config")
+
+	// 默认值
+	viper.SetDefault("port", "8080")
+	viper.SetDefault("jwt_secret", "your-secret-key-change-in-production")
+	viper.SetDefault("python_service_url", "http://localhost:8081")
+	viper.SetDefault("database_url", "root:root@tcp(localhost:3306)/x_agents?charset=utf8mb4&parseTime=True&loc=Local")
+
+	if err := viper.ReadInConfig(); err != nil {
+		log.Printf("Using default config: %v", err)
+	}
+
+	return &Config{
+		Port:              viper.GetString("port"),
+		JWTSecret:         viper.GetString("jwt_secret"),
+		DatabaseURL:       viper.GetString("database_url"),
+		PythonServiceURL: viper.GetString("python_service_url"),
+	}
+}
+
+func InitDB(cfg *Config) (*gorm.DB, error) {
+	dsn := cfg.DatabaseURL
+	if dsn == "" {
+		return nil, fmt.Errorf("database URL is empty")
+	}
+
+	db, err := gorm.Open(mysql.Open(dsn), &gorm.Config{
+		Logger: logger.Default.LogMode(logger.Info),
+	})
+	if err != nil {
+		return nil, fmt.Errorf("failed to connect database: %w", err)
+	}
+
+	log.Println("Database connected successfully")
+	return db, nil
+}